Номер 12, страница 7, часть 2 - гдз по физике 9 класс рабочая тетрадь Грачев, Погожев

Авторы: Грачев А. В., Погожев В. А., Боков П. Ю., Вишнякова Е. А.

Тип: рабочая тетрадь

Издательство: Просвещение

Год издания: 2021 - 2026

Часть: 2

Цвет обложки: синий

ISBN: 978-5-09-098826-1 (ч.1) 978-5-09-098880-3 (ч.2) 978-5-09-098881-0 (ч.3)

Часть 2. Глава 3. Импульс. Закон сохранения импульса. Параграф 23. Импульс. Изменение импульса материальной точки. Система тел. Закон сохранения импульса - номер 12, страница 7.

App\Models\Task {#1030 // resources/views/models/task/default.blade.php
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  #table: "tasks"
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      #items: array:1 [
        0 => App\Models\Term {#1036
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                          #table: "terms"
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                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:10 [
                            "id" => 6736
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "рабочая тетрадь"
                            "field_book_type_foreign" => null
                            "field_cases" => array:6 [
                              "field_accusative_case" => "рабочую тетрадь"
                              "field_creative_case" => "рабочей тетрадью"
                              "field_dative_case" => "рабочей тетради"
                              "field_genitive_case" => "рабочей тетради"
                              "field_nominative_case" => "рабочая тетрадь"
                              "field_prepositional_case" => "рабочей тетради"
                            ]
                            "field_plural_form" => "рабочие тетради"
                            "field_short_name" => "рт"
                            "field_short_name_foreign" => null
                            "field_translit" => "rabochaya tetrad"
                          ]
                          #original: array:10 [
                            "id" => 6736
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "рабочая тетрадь"
                            "field_book_type_foreign" => null
                            "field_cases" => array:6 [
                              "field_accusative_case" => "рабочую тетрадь"
                              "field_creative_case" => "рабочей тетрадью"
                              "field_dative_case" => "рабочей тетради"
                              "field_genitive_case" => "рабочей тетради"
                              "field_nominative_case" => "рабочая тетрадь"
                              "field_prepositional_case" => "рабочей тетради"
                            ]
                            "field_plural_form" => "рабочие тетради"
                            "field_short_name" => "рт"
                            "field_short_name_foreign" => null
                            "field_translit" => "rabochaya tetrad"
                          ]
                          #changes: []
                          #casts: []
                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
                          +usesUniqueIds: false
                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1064
                      #items: array:1 [
                        0 => App\Models\Term {#1065
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:6 [
                            "id" => 9
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Россия"
                            "field_cases" => array:6 [
                              "field_accusative_case" => null
                              "field_creative_case" => null
                              "field_dative_case" => null
                              "field_genitive_case" => null
                              "field_nominative_case" => null
                              "field_prepositional_case" => null
                            ]
                            "field_translit" => "rossiya"
                          ]
                          #original: array:6 [
                            "id" => 9
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Россия"
                            "field_cases" => array:6 [
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                              "field_dative_case" => null
                              "field_genitive_case" => null
                              "field_nominative_case" => null
                              "field_prepositional_case" => null
                            ]
                            "field_translit" => "rossiya"
                          ]
                          #changes: []
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                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
                          +usesUniqueIds: false
                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1066
                      #items: array:1 [
                        0 => App\Models\Term {#1067
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:6 [
                            "id" => 15
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Москва"
                            "field_cases" => array:6 [
                              "field_accusative_case" => null
                              "field_creative_case" => null
                              "field_dative_case" => null
                              "field_genitive_case" => null
                              "field_nominative_case" => null
                              "field_prepositional_case" => null
                            ]
                            "field_translit" => "moskva"
                          ]
                          #original: array:6 [
                            "id" => 15
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Москва"
                            "field_cases" => array:6 [
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                              "field_prepositional_case" => null
                            ]
                            "field_translit" => "moskva"
                          ]
                          #changes: []
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                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
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                          #hidden: []
                          #visible: []
                          #fillable: []
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                            0 => "*"
                          ]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_series" => Illuminate\Database\Eloquent\Collection {#1068
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1069
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1070
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1071
                      #items: array:1 [
                        0 => App\Models\Term {#1072
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:10 [
                            "id" => 6706
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "ФГОС (старый)"
                            "field_cases" => array:6 [
                              "field_accusative_case" => null
                              "field_creative_case" => null
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                              "field_genitive_case" => null
                              "field_nominative_case" => null
                              "field_prepositional_case" => null
                            ]
                            "field_color" => null
                            "field_end_year" => "2022"
                            "field_start_year" => "2019"
                            "field_translit" => "fgos-old"
                            "field_type" => null
                          ]
                          #original: array:10 [
                            "id" => 6706
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "ФГОС (старый)"
                            "field_cases" => array:6 [
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                            ]
                            "field_color" => null
                            "field_end_year" => "2022"
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                            "field_translit" => "fgos-old"
                            "field_type" => null
                          ]
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                          #dateFormat: null
                          #appends: []
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                          #touches: []
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                          +usesUniqueIds: false
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                          ]
                        }
                      ]
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                    }
                    "field_publication_number" => "6"
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1073
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                        0 => App\Models\Term {#1074
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
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                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:6 [
                            "id" => 33
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "стереотипное"
                            "field_cases" => array:6 [
                              "field_accusative_case" => null
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                              "field_genitive_case" => null
                              "field_nominative_case" => null
                              "field_prepositional_case" => null
                            ]
                            "field_translit" => "stereotipnoe"
                          ]
                          #original: array:6 [
                            "id" => 33
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "стереотипное"
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                              "field_nominative_case" => null
                              "field_prepositional_case" => null
                            ]
                            "field_translit" => "stereotipnoe"
                          ]
                          #changes: []
                          #casts: []
                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
                          +usesUniqueIds: false
                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1075
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_under_the_edition_degree" => null
                    "field_cover_description" => null
                    "field_publication_year" => "2021"
                    "field_publication_year_until" => null
                    "field_part" => "1, 2, 3"
                    "field_part_writing" => "Часть"
                    "field_second_foreign_language" => null
                    "field_for_whom" => "Учебное издание"
                    "field_allowed" => null
                    "field_reserve_field" => null
                    "field_link_to_source" => null
                    "field_tasks_count" => "594"
                    "field_priority" => null
                    "field_default_folder" => "/fizika_09/grachev-rt/"
                    "field_isbn" => "978-5-09-098826-1 (ч.1) 978-5-09-098880-3 (ч.2) 978-5-09-098881-0 (ч.3)"
                    "field_cover" => array:3 [
                      0 => "/media/fizika_09/grachev-rt/covers/cover1.webp?ts=1759003248"
                      1 => "/media/fizika_09/grachev-rt/covers/cover2.webp?ts=1759003248"
                      2 => "/media/fizika_09/grachev-rt/covers/cover3.webp?ts=1759003248"
                    ]
                    "field_cover_alts" => array:3 [
                      0 => ""
                      1 => ""
                      2 => ""
                    ]
                    "field_covers" => array:3 [
                      0 => array:4 [
                        "path" => "/media/fizika_09/grachev-rt/covers/cover1.webp?ts=1759003248"
                        "alt" => ""
                        "width" => "2293"
                        "height" => "2989"
                      ]
                      1 => array:4 [
                        "path" => "/media/fizika_09/grachev-rt/covers/cover2.webp?ts=1759003248"
                        "alt" => ""
                        "width" => "2265"
                        "height" => "3003"
                      ]
                      2 => array:4 [
                        "path" => "/media/fizika_09/grachev-rt/covers/cover3.webp?ts=1759003248"
                        "alt" => ""
                        "width" => "2241"
                        "height" => "2999"
                      ]
                    ]
                    "field_popular_book" => "0"
                    "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1076
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1077
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1078
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_url" => "/9-klass/fizika/grachev-rabochaya-tetrad"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1079
                      #items: array:1 [
                        0 => App\Models\Term {#1080
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:6 [
                            "id" => 49
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "синий"
                            "field_cases" => array:6 [
                              "field_accusative_case" => null
                              "field_creative_case" => null
                              "field_dative_case" => null
                              "field_genitive_case" => null
                              "field_nominative_case" => null
                              "field_prepositional_case" => null
                            ]
                            "field_translit" => "siniy"
                          ]
                          #original: array:6 [
                            "id" => 49
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "синий"
                            "field_cases" => array:6 [
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                              "field_prepositional_case" => null
                            ]
                            "field_translit" => "siniy"
                          ]
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                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
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                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
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                    "field_description_bottom" => null
                    "breadcrumbs" => array:3 [
                      "class" => 380
                      "subject" => 556
                      "class_subject" => 493
                    ]
                  ]
                  #original: array:50 [
                    "id" => 1203
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_tree_default_status" => "tasks"
                    "field_pages_status" => null
                    "field_subject" => Illuminate\Database\Eloquent\Collection {#1051}
                    "field_class" => Illuminate\Database\Eloquent\Collection {#1052}
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1054}
                    "field_author" => Illuminate\Database\Eloquent\Collection {#1056}
                    "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1061}
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1062}
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1064}
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1066}
                    "field_series" => Illuminate\Database\Eloquent\Collection {#1068}
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1069}
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1070}
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1071}
                    "field_publication_number" => "6"
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1073}
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1075}
                    "field_under_the_edition_degree" => null
                    "field_cover_description" => null
                    "field_publication_year" => "2021"
                    "field_publication_year_until" => null
                    "field_part" => "1, 2, 3"
                    "field_part_writing" => "Часть"
                    "field_second_foreign_language" => null
                    "field_for_whom" => "Учебное издание"
                    "field_allowed" => null
                    "field_reserve_field" => null
                    "field_link_to_source" => null
                    "field_tasks_count" => "594"
                    "field_priority" => null
                    "field_default_folder" => "/fizika_09/grachev-rt/"
                    "field_isbn" => "978-5-09-098826-1 (ч.1) 978-5-09-098880-3 (ч.2) 978-5-09-098881-0 (ч.3)"
                    "field_cover" => array:3 [
                      0 => "/media/fizika_09/grachev-rt/covers/cover1.webp?ts=1759003248"
                      1 => "/media/fizika_09/grachev-rt/covers/cover2.webp?ts=1759003248"
                      2 => "/media/fizika_09/grachev-rt/covers/cover3.webp?ts=1759003248"
                    ]
                    "field_cover_alts" => array:3 [
                      0 => ""
                      1 => ""
                      2 => ""
                    ]
                    "field_covers" => array:3 [
                      0 => array:4 [
                        "path" => "/media/fizika_09/grachev-rt/covers/cover1.webp?ts=1759003248"
                        "alt" => ""
                        "width" => "2293"
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                      ]
                      1 => array:4 [
                        "path" => "/media/fizika_09/grachev-rt/covers/cover2.webp?ts=1759003248"
                        "alt" => ""
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                      ]
                      2 => array:4 [
                        "path" => "/media/fizika_09/grachev-rt/covers/cover3.webp?ts=1759003248"
                        "alt" => ""
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                        "height" => "2999"
                      ]
                    ]
                    "field_popular_book" => "0"
                    "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1076}
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1077}
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1078}
                    "field_url" => "/9-klass/fizika/grachev-rabochaya-tetrad"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1079}
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
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                    "breadcrumbs" => array:3 [
                      "class" => 380
                      "subject" => 556
                      "class_subject" => 493
                    ]
                  ]
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                  #attributeCastCache: []
                  #dateFormat: null
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                  #dispatchesEvents: []
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                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1081
              #items: []
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1434829
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => null
            "field_branch_order" => "2"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1050}
            "field_page_start" => "3"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
            "field_display_task_interval" => "0"
            "field_display_branch_page" => "1"
            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
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            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1083}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1081}
          ]
          #changes: []
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          #attributeCastCache: []
          #dateFormat: null
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          #dispatchesEvents: []
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          #relations: []
          #touches: []
          +timestamps: true
          +usesUniqueIds: false
          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
      ]
      #escapeWhenCastingToString: false
    }
    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1114
      #items: array:3 [
        0 => App\Models\Branch {#1124
          #connection: "mysql"
          #table: "branches"
          #primaryKey: "id"
          #keyType: "int"
          +incrementing: true
          #with: []
          #withCount: []
          +preventsLazyLoading: false
          #perPage: 15
          +exists: true
          +wasRecentlyCreated: false
          #escapeWhenCastingToString: false
          #attributes: array:24 [
            "id" => 1434829
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => null
            "field_branch_order" => "2"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1125
              #items: array:1 [
                0 => App\Models\Term {#1047}
              ]
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "3"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
            "field_display_task_interval" => "0"
            "field_display_branch_page" => "1"
            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1126
              #items: array:1 [
                0 => App\Models\Book {#1049}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1127
              #items: []
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1434829
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => null
            "field_branch_order" => "2"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1125}
            "field_page_start" => "3"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
            "field_display_task_interval" => "0"
            "field_display_branch_page" => "1"
            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1126}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1127}
          ]
          #changes: []
          #casts: []
          #classCastCache: []
          #attributeCastCache: []
          #dateFormat: null
          #appends: []
          #dispatchesEvents: []
          #observables: []
          #relations: []
          #touches: []
          +timestamps: true
          +usesUniqueIds: false
          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
        1 => App\Models\Branch {#1128
          #connection: "mysql"
          #table: "branches"
          #primaryKey: "id"
          #keyType: "int"
          +incrementing: true
          #with: []
          #withCount: []
          +preventsLazyLoading: false
          #perPage: 15
          +exists: true
          +wasRecentlyCreated: false
          #escapeWhenCastingToString: false
          #attributes: array:24 [
            "id" => 1434830
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Импульс. Закон сохранения импульса"
            "field_branch_order" => "3"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1132
              #items: array:1 [
                0 => App\Models\Term {#1129
                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:7 [
                    "id" => 29
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Глава"
                    "field_cases" => array:6 [
                      "field_accusative_case" => "Главу"
                      "field_creative_case" => "Главой"
                      "field_dative_case" => "Главе"
                      "field_genitive_case" => "Главы"
                      "field_nominative_case" => "Глава"
                      "field_prepositional_case" => "Главе"
                    ]
                    "field_page_check_not_needed" => null
                    "field_short_name" => null
                  ]
                  #original: array:7 [
                    "id" => 29
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Глава"
                    "field_cases" => array:6 [
                      "field_accusative_case" => "Главу"
                      "field_creative_case" => "Главой"
                      "field_dative_case" => "Главе"
                      "field_genitive_case" => "Главы"
                      "field_nominative_case" => "Глава"
                      "field_prepositional_case" => "Главе"
                    ]
                    "field_page_check_not_needed" => null
                    "field_short_name" => null
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "3"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
            "field_display_task_interval" => "0"
            "field_display_branch_page" => "1"
            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1131
              #items: array:1 [
                0 => App\Models\Book {#1049}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1130
              #items: array:1 [
                0 => App\Models\Branch {#1045}
              ]
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1434830
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Импульс. Закон сохранения импульса"
            "field_branch_order" => "3"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1132}
            "field_page_start" => "3"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
            "field_display_task_interval" => "0"
            "field_display_branch_page" => "1"
            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1131}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1130}
          ]
          #changes: []
          #casts: []
          #classCastCache: []
          #attributeCastCache: []
          #dateFormat: null
          #appends: []
          #dispatchesEvents: []
          #observables: []
          #relations: []
          #touches: []
          +timestamps: true
          +usesUniqueIds: false
          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
        2 => App\Models\Branch {#1133
          #connection: "mysql"
          #table: "branches"
          #primaryKey: "id"
          #keyType: "int"
          +incrementing: true
          #with: []
          #withCount: []
          +preventsLazyLoading: false
          #perPage: 15
          +exists: true
          +wasRecentlyCreated: false
          #escapeWhenCastingToString: false
          #attributes: array:24 [
            "id" => 1434831
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Импульс. Изменение импульса материальной точки. Система тел. Закон сохранения импульса"
            "field_branch_order" => "23"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1137
              #items: array:1 [
                0 => App\Models\Term {#1134
                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:7 [
                    "id" => 32
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Параграф"
                    "field_cases" => array:6 [
                      "field_accusative_case" => "Параграф"
                      "field_creative_case" => "Параграфом"
                      "field_dative_case" => "Параграфу"
                      "field_genitive_case" => "Параграфа"
                      "field_nominative_case" => "Параграф"
                      "field_prepositional_case" => "Параграфе"
                    ]
                    "field_page_check_not_needed" => null
                    "field_short_name" => "§"
                  ]
                  #original: array:7 [
                    "id" => 32
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Параграф"
                    "field_cases" => array:6 [
                      "field_accusative_case" => "Параграф"
                      "field_creative_case" => "Параграфом"
                      "field_dative_case" => "Параграфу"
                      "field_genitive_case" => "Параграфа"
                      "field_nominative_case" => "Параграф"
                      "field_prepositional_case" => "Параграфе"
                    ]
                    "field_page_check_not_needed" => null
                    "field_short_name" => "§"
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "3"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
            "field_display_task_interval" => "0"
            "field_display_branch_page" => "1"
            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1136
              #items: array:1 [
                0 => App\Models\Book {#1049}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1145
              #items: array:1 [
                0 => App\Models\Branch {#1144
                  #connection: "mysql"
                  #table: "branches"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:24 [
                    "id" => 1434830
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Импульс. Закон сохранения импульса"
                    "field_branch_order" => "3"
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1146
                      #items: array:1 [
                        0 => App\Models\Term {#1129}
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_page_start" => "3"
                    "field_branch_display" => "0"
                    "field_branch_expanded" => "0"
                    "field_display_branch_in_title" => "1"
                    "field_display_task_interval" => "0"
                    "field_display_branch_page" => "1"
                    "field_branch_title_in_content" => "0"
                    "field_navigation_title" => null
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "field_branch_cover" => []
                    "field_branch_covers" => []
                    "book" => Illuminate\Database\Eloquent\Collection {#1147
                      #items: array:1 [
                        0 => App\Models\Book {#1049}
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1148
                      #items: array:1 [
                        0 => App\Models\Branch {#1045}
                      ]
                      #escapeWhenCastingToString: false
                    }
                  ]
                  #original: array:24 [
                    "id" => 1434830
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Импульс. Закон сохранения импульса"
                    "field_branch_order" => "3"
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1146}
                    "field_page_start" => "3"
                    "field_branch_display" => "0"
                    "field_branch_expanded" => "0"
                    "field_display_branch_in_title" => "1"
                    "field_display_task_interval" => "0"
                    "field_display_branch_page" => "1"
                    "field_branch_title_in_content" => "0"
                    "field_navigation_title" => null
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "field_branch_cover" => []
                    "field_branch_covers" => []
                    "book" => Illuminate\Database\Eloquent\Collection {#1147}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1148}
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1434831
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Импульс. Изменение импульса материальной точки. Система тел. Закон сохранения импульса"
            "field_branch_order" => "23"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1137}
            "field_page_start" => "3"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
            "field_display_task_interval" => "0"
            "field_display_branch_page" => "1"
            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1136}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1145}
          ]
          #changes: []
          #casts: []
          #classCastCache: []
          #attributeCastCache: []
          #dateFormat: null
          #appends: []
          #dispatchesEvents: []
          #observables: []
          #relations: []
          #touches: []
          +timestamps: true
          +usesUniqueIds: false
          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
      ]
      #escapeWhenCastingToString: false
    }
    "content" => Illuminate\Database\Eloquent\Collection {#1106
      #items: array:2 [
        0 => App\Models\Element {#1097
          #connection: "mysql"
          #table: "elements"
          #primaryKey: "id"
          #keyType: "int"
          +incrementing: true
          #with: []
          #withCount: []
          +preventsLazyLoading: false
          #perPage: 15
          +exists: true
          +wasRecentlyCreated: false
          #escapeWhenCastingToString: false
          #attributes: array:7 [
            "id" => 1698427
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1090
              #items: array:1 [
                0 => App\Models\Edition {#1098
                  #connection: "mysql"
                  #table: "editions"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:21 [
                    "id" => 6173
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "title" => "Условие"
                    "field_order" => "1"
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1096
                      #items: array:1 [
                        0 => App\Models\Term {#1095
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:6 [ …6]
                          #original: array:6 [ …6]
                          #changes: []
                          #casts: []
                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
                          +usesUniqueIds: false
                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [ …1]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_content_type" => "free"
                    "field_content_mode" => "text, image"
                    "field_page_content_mode" => "image"
                    "field_content_text_checked" => null
                    "field_page_content_text_checked" => "0"
                    "field_solution_author" => "Автор"
                    "field_moderator" => "stas"
                    "field_edition_type" => "statement"
                    "field_root_dir" => "0-"
                    "field_responsible" => Illuminate\Database\Eloquent\Collection {#1093
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1094
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_process_formula" => "katex"
                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1092
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_content_source" => null
                  ]
                  #original: array:21 [
                    "id" => 6173
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "title" => "Условие"
                    "field_order" => "1"
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1096}
                    "field_content_type" => "free"
                    "field_content_mode" => "text, image"
                    "field_page_content_mode" => "image"
                    "field_content_text_checked" => null
                    "field_page_content_text_checked" => "0"
                    "field_solution_author" => "Автор"
                    "field_moderator" => "stas"
                    "field_edition_type" => "statement"
                    "field_root_dir" => "0-"
                    "field_responsible" => Illuminate\Database\Eloquent\Collection {#1093}
                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1094}
                    "field_process_formula" => "katex"
                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1092}
                    "field_content_source" => null
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "task" => array:2 [
              "refs" => "1435039"
              "type" => "task"
            ]
            "text" => "<p><strong>12.</strong> Материальная точка массой 5 кг движется в ИСО вдоль оси Х по закону: $x = 2,5 + 4t - 2t^2$. Все величины в этом законе измерены в СИ. Движение начинается в момент времени $t = 0$. Определите: а) зависимость модуля импульса точки от времени; б) модуль изменения импульса точки за 10 с после начала движения; в) модуль и направление суммы сил, действующих на точку.</p><p><em>Решение.</em></p><p><em>Ответ:</em> а) ___________ ; б) ___________ ; в) ___________</p>"
            "img" => array:1 [
              0 => array:5 [
                "name" => "12-1.jpg"
                "alt" => null
                "width" => "1971"
                "height" => 754
                "path" => "/media/fizika_09/grachev-rt/0-23/12-1.webp?ts=1759402717"
              ]
            ]
          ]
          #original: array:7 [
            "id" => 1698427
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1090}
            "task" => array:2 [
              "refs" => "1435039"
              "type" => "task"
            ]
            "text" => "<p><strong>12.</strong> Материальная точка массой 5 кг движется в ИСО вдоль оси Х по закону: $x = 2,5 + 4t - 2t^2$. Все величины в этом законе измерены в СИ. Движение начинается в момент времени $t = 0$. Определите: а) зависимость модуля импульса точки от времени; б) модуль изменения импульса точки за 10 с после начала движения; в) модуль и направление суммы сил, действующих на точку.</p><p><em>Решение.</em></p><p><em>Ответ:</em> а) ___________ ; б) ___________ ; в) ___________</p>"
            "img" => array:1 [
              0 => array:5 [
                "name" => "12-1.jpg"
                "alt" => null
                "width" => "1971"
                "height" => 754
                "path" => "/media/fizika_09/grachev-rt/0-23/12-1.webp?ts=1759402717"
              ]
            ]
          ]
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          ]
        }
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          #table: "elements"
          #primaryKey: "id"
          #keyType: "int"
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          #perPage: 15
          +exists: true
          +wasRecentlyCreated: false
          #escapeWhenCastingToString: false
          #attributes: array:6 [
            "id" => 1734413
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1041
              #items: array:1 [
                0 => App\Models\Edition {#1091
                  #connection: "mysql"
                  #table: "editions"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:21 [
                    "id" => 6327
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "title" => "Решение"
                    "field_order" => "2"
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1088
                      #items: array:1 [
                        0 => App\Models\Term {#1089
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:6 [ …6]
                          #original: array:6 [ …6]
                          #changes: []
                          #casts: []
                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
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                          #touches: []
                           …6
                        }
                      ]
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                    "field_content_type" => "free"
                    "field_content_mode" => "text"
                    "field_page_content_mode" => ""
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                    "field_page_content_text_checked" => "0"
                    "field_solution_author" => "Gemini 2.5 Pro"
                    "field_moderator" => "tolik"
                    "field_edition_type" => "solution"
                    "field_root_dir" => "1-"
                    "field_responsible" => Illuminate\Database\Eloquent\Collection {#1085
                      #items: []
                      #escapeWhenCastingToString: false
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                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1086
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_process_formula" => "katex"
                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1082
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_content_source" => null
                  ]
                  #original: array:21 [
                    "id" => 6327
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "title" => "Решение"
                    "field_order" => "2"
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1088}
                    "field_content_type" => "free"
                    "field_content_mode" => "text"
                    "field_page_content_mode" => ""
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                    "field_page_content_text_checked" => "0"
                    "field_solution_author" => "Gemini 2.5 Pro"
                    "field_moderator" => "tolik"
                    "field_edition_type" => "solution"
                    "field_root_dir" => "1-"
                    "field_responsible" => Illuminate\Database\Eloquent\Collection {#1085}
                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1086}
                    "field_process_formula" => "katex"
                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1082}
                    "field_content_source" => null
                  ]
                  #changes: []
                  #casts: []
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                  #attributeCastCache: []
                  #dateFormat: null
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                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
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                    0 => "*"
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                }
              ]
              #escapeWhenCastingToString: false
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            "task" => array:2 [
              "refs" => "1435039"
              "type" => "task"
            ]
            "text" => "<p><strong>Дано:</strong></p><p>$m = 5$ кг</p><p>$x(t) = 2,5 + 4t - 2t^2$ (СИ)</p><p>$t_0 = 0$ с</p><p>$t = 10$ с</p><p><strong>Найти:</strong></p><p>а) $p(t) - ?$</p><p>б) $|\Delta p| - ?$</p><p>в) $F, \text{направление } \vec{F} - ?$</p><p><strong>Решение:</strong></p><p><strong>а) зависимость модуля импульса точки от времени</strong></p><p>Импульс материальной точки определяется формулой $\vec{p} = m \cdot \vec{v}$. Для нахождения зависимости импульса от времени, сначала найдем зависимость скорости от времени. Скорость является первой производной координаты по времени:</p><p>$v_x(t) = x'(t) = \frac{d}{dt}(2,5 + 4t - 2t^2) = 4 - 4t$ (м/с).</p><p>Проекция импульса на ось X равна:</p><p>$p_x(t) = m \cdot v_x(t) = 5 \cdot (4 - 4t) = 20 - 20t$ (кг·м/с).</p><p>Модуль импульса – это абсолютное значение его проекции (так как движение одномерное):</p><p>$p(t) = |p_x(t)| = |20 - 20t| = 20|1 - t|$ (кг·м/с).</p><p><strong>Ответ:</strong> $p(t) = 20|1 - t|$ (кг·м/с).</p><p><strong>б) модуль изменения импульса точки за 10 с после начала движения</strong></p><p>Изменение импульса $\Delta \vec{p}$ равно разности конечного и начального импульсов: $\Delta \vec{p} = \vec{p}(t) - \vec{p}(t_0)$.</p><p>Начальный момент времени $t_0 = 0$ с, конечный – $t = 10$ с.</p><p>Найдем проекцию импульса в эти моменты времени, используя полученную в пункте а) формулу $p_x(t) = 20 - 20t$:</p><p>Начальный импульс: $p_x(0) = 20 - 20 \cdot 0 = 20$ кг·м/с.</p><p>Конечный импульс: $p_x(10) = 20 - 20 \cdot 10 = 20 - 200 = -180$ кг·м/с.</p><p>Изменение проекции импульса:</p><p>$\Delta p_x = p_x(10) - p_x(0) = -180 - 20 = -200$ кг·м/с.</p><p>Модуль изменения импульса равен модулю изменения проекции:</p><p>$|\Delta p| = |\Delta p_x| = |-200| = 200$ кг·м/с.</p><p><strong>Ответ:</strong> 200 кг·м/с.</p><p><strong>в) модуль и направление суммы сил, действующих на точку</strong></p><p>Согласно второму закону Ньютона, равнодействующая (сумма) всех сил, действующих на точку, равна произведению массы точки на ее ускорение: $\vec{F} = m \cdot \vec{a}$.</p><p>Ускорение является первой производной скорости по времени:</p><p>$a_x(t) = v_x'(t) = \frac{d}{dt}(4 - 4t) = -4$ м/с².</p><p>Ускорение точки постоянно и не зависит от времени. Найдем проекцию силы на ось X:</p><p>$F_x = m \cdot a_x = 5 \cdot (-4) = -20$ Н.</p><p>Модуль силы равен:</p><p>$F = |F_x| = |-20| = 20$ Н.</p><p>Так как проекция силы $F_x$ отрицательна, вектор силы $\vec{F}$ направлен в сторону, противоположную положительному направлению оси X.</p><p><strong>Ответ:</strong> Модуль силы равен 20 Н, сила направлена противоположно положительному направлению оси X.</p>"
          ]
          #original: array:6 [
            "id" => 1734413
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1041}
            "task" => array:2 [
              "refs" => "1435039"
              "type" => "task"
            ]
            "text" => "<p><strong>Дано:</strong></p><p>$m = 5$ кг</p><p>$x(t) = 2,5 + 4t - 2t^2$ (СИ)</p><p>$t_0 = 0$ с</p><p>$t = 10$ с</p><p><strong>Найти:</strong></p><p>а) $p(t) - ?$</p><p>б) $|\Delta p| - ?$</p><p>в) $F, \text{направление } \vec{F} - ?$</p><p><strong>Решение:</strong></p><p><strong>а) зависимость модуля импульса точки от времени</strong></p><p>Импульс материальной точки определяется формулой $\vec{p} = m \cdot \vec{v}$. Для нахождения зависимости импульса от времени, сначала найдем зависимость скорости от времени. Скорость является первой производной координаты по времени:</p><p>$v_x(t) = x'(t) = \frac{d}{dt}(2,5 + 4t - 2t^2) = 4 - 4t$ (м/с).</p><p>Проекция импульса на ось X равна:</p><p>$p_x(t) = m \cdot v_x(t) = 5 \cdot (4 - 4t) = 20 - 20t$ (кг·м/с).</p><p>Модуль импульса – это абсолютное значение его проекции (так как движение одномерное):</p><p>$p(t) = |p_x(t)| = |20 - 20t| = 20|1 - t|$ (кг·м/с).</p><p><strong>Ответ:</strong> $p(t) = 20|1 - t|$ (кг·м/с).</p><p><strong>б) модуль изменения импульса точки за 10 с после начала движения</strong></p><p>Изменение импульса $\Delta \vec{p}$ равно разности конечного и начального импульсов: $\Delta \vec{p} = \vec{p}(t) - \vec{p}(t_0)$.</p><p>Начальный момент времени $t_0 = 0$ с, конечный – $t = 10$ с.</p><p>Найдем проекцию импульса в эти моменты времени, используя полученную в пункте а) формулу $p_x(t) = 20 - 20t$:</p><p>Начальный импульс: $p_x(0) = 20 - 20 \cdot 0 = 20$ кг·м/с.</p><p>Конечный импульс: $p_x(10) = 20 - 20 \cdot 10 = 20 - 200 = -180$ кг·м/с.</p><p>Изменение проекции импульса:</p><p>$\Delta p_x = p_x(10) - p_x(0) = -180 - 20 = -200$ кг·м/с.</p><p>Модуль изменения импульса равен модулю изменения проекции:</p><p>$|\Delta p| = |\Delta p_x| = |-200| = 200$ кг·м/с.</p><p><strong>Ответ:</strong> 200 кг·м/с.</p><p><strong>в) модуль и направление суммы сил, действующих на точку</strong></p><p>Согласно второму закону Ньютона, равнодействующая (сумма) всех сил, действующих на точку, равна произведению массы точки на ее ускорение: $\vec{F} = m \cdot \vec{a}$.</p><p>Ускорение является первой производной скорости по времени:</p><p>$a_x(t) = v_x'(t) = \frac{d}{dt}(4 - 4t) = -4$ м/с².</p><p>Ускорение точки постоянно и не зависит от времени. Найдем проекцию силы на ось X:</p><p>$F_x = m \cdot a_x = 5 \cdot (-4) = -20$ Н.</p><p>Модуль силы равен:</p><p>$F = |F_x| = |-20| = 20$ Н.</p><p>Так как проекция силы $F_x$ отрицательна, вектор силы $\vec{F}$ направлен в сторону, противоположную положительному направлению оси X.</p><p><strong>Ответ:</strong> Модуль силы равен 20 Н, сила направлена противоположно положительному направлению оси X.</p>"
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    "book" => Illuminate\Database\Eloquent\Collection {#1101
      #items: array:1 [
        0 => App\Models\Book {#1049}
      ]
      #escapeWhenCastingToString: false
    }
    "page" => Illuminate\Database\Eloquent\Collection {#1042
      #items: array:1 [
        0 => App\Models\BookPage {#1110
          #connection: "mysql"
          #table: "book_pages"
          #primaryKey: "id"
          #keyType: "int"
          +incrementing: true
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          +preventsLazyLoading: false
          #perPage: 15
          +exists: true
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            "created_at" => "2026-04-10 13:58:26"
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            "field_url" => "/9-klass/fizika/grachev-rabochaya-tetrad/page-3-7"
            "field_display_title" => "7"
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                0 => App\Models\Branch {#1040
                  #connection: "mysql"
                  #table: "branches"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
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                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
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                    "created_at" => "2026-04-10 13:58:26"
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                    "field_url" => null
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                        0 => App\Models\Term {#1107 …30}
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                    "book" => Illuminate\Database\Eloquent\Collection {#1099
                      #items: array:1 [
                        0 => App\Models\Book {#1102 …30}
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                      #escapeWhenCastingToString: false
                    }
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1159
                      #items: []
                      #escapeWhenCastingToString: false
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                    "created_at" => "2026-04-10 13:58:26"
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                    "field_branch_order" => "3"
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1108}
                    "field_page_start" => "3"
                    "field_branch_display" => "0"
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              #items: []
              #escapeWhenCastingToString: false
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              #items: array:1 [
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                  #connection: "mysql"
                  #table: "elements"
                  #primaryKey: "id"
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                  +incrementing: true
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                    "created_at" => "2026-04-10 13:58:26"
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                      #items: array:1 [
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                    "edition" => Illuminate\Database\Eloquent\Collection {#1173}
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№12 (с. 7)
Условие. №12 (с. 7)
скриншот условия
Физика, 9 класс рабочая тетрадь, авторы: Грачев Александр Васильевич, Погожев Владимир Александрович, Боков Павел Юрьевич, Вишнякова Екатерина Анатольевна, издательство Просвещение, Москва, 2021, Часть 2, страница 7, номер 12, Условие

12. Материальная точка массой 5 кг движется в ИСО вдоль оси Х по закону: $x = 2,5 + 4t - 2t^2$. Все величины в этом законе измерены в СИ. Движение начинается в момент времени $t = 0$. Определите: а) зависимость модуля импульса точки от времени; б) модуль изменения импульса точки за 10 с после начала движения; в) модуль и направление суммы сил, действующих на точку.

Решение.

Ответ: а) ___________ ; б) ___________ ; в) ___________

Решение. №12 (с. 7)

Дано:

$m = 5$ кг

$x(t) = 2,5 + 4t - 2t^2$ (СИ)

$t_0 = 0$ с

$t = 10$ с

Найти:

а) $p(t) - ?$

б) $|\Delta p| - ?$

в) $F, \text{направление } \vec{F} - ?$

Решение:

а) зависимость модуля импульса точки от времени

Импульс материальной точки определяется формулой $\vec{p} = m \cdot \vec{v}$. Для нахождения зависимости импульса от времени, сначала найдем зависимость скорости от времени. Скорость является первой производной координаты по времени:

$v_x(t) = x'(t) = \frac{d}{dt}(2,5 + 4t - 2t^2) = 4 - 4t$ (м/с).

Проекция импульса на ось X равна:

$p_x(t) = m \cdot v_x(t) = 5 \cdot (4 - 4t) = 20 - 20t$ (кг·м/с).

Модуль импульса – это абсолютное значение его проекции (так как движение одномерное):

$p(t) = |p_x(t)| = |20 - 20t| = 20|1 - t|$ (кг·м/с).

Ответ: $p(t) = 20|1 - t|$ (кг·м/с).

б) модуль изменения импульса точки за 10 с после начала движения

Изменение импульса $\Delta \vec{p}$ равно разности конечного и начального импульсов: $\Delta \vec{p} = \vec{p}(t) - \vec{p}(t_0)$.

Начальный момент времени $t_0 = 0$ с, конечный – $t = 10$ с.

Найдем проекцию импульса в эти моменты времени, используя полученную в пункте а) формулу $p_x(t) = 20 - 20t$:

Начальный импульс: $p_x(0) = 20 - 20 \cdot 0 = 20$ кг·м/с.

Конечный импульс: $p_x(10) = 20 - 20 \cdot 10 = 20 - 200 = -180$ кг·м/с.

Изменение проекции импульса:

$\Delta p_x = p_x(10) - p_x(0) = -180 - 20 = -200$ кг·м/с.

Модуль изменения импульса равен модулю изменения проекции:

$|\Delta p| = |\Delta p_x| = |-200| = 200$ кг·м/с.

Ответ: 200 кг·м/с.

в) модуль и направление суммы сил, действующих на точку

Согласно второму закону Ньютона, равнодействующая (сумма) всех сил, действующих на точку, равна произведению массы точки на ее ускорение: $\vec{F} = m \cdot \vec{a}$.

Ускорение является первой производной скорости по времени:

$a_x(t) = v_x'(t) = \frac{d}{dt}(4 - 4t) = -4$ м/с².

Ускорение точки постоянно и не зависит от времени. Найдем проекцию силы на ось X:

$F_x = m \cdot a_x = 5 \cdot (-4) = -20$ Н.

Модуль силы равен:

$F = |F_x| = |-20| = 20$ Н.

Так как проекция силы $F_x$ отрицательна, вектор силы $\vec{F}$ направлен в сторону, противоположную положительному направлению оси X.

Ответ: Модуль силы равен 20 Н, сила направлена противоположно положительному направлению оси X.

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