Номер 10, страница 20, 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 4. Механическая работа. Механическая энергия. Закон сохранения механической энергии. Параграф 25. Общее определение механической работы. Мощность - номер 10, страница 20.

App\Models\Task {#1030 // resources/views/models/task/default.blade.php
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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 {#1188
      #items: array:3 [
        0 => App\Models\Branch {#1198
          #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 {#1199
              #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 {#1200
              #items: array:1 [
                0 => App\Models\Book {#1049}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1201
              #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 {#1199}
            "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 {#1200}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1201}
          ]
          #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 {#1202
          #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" => 1434833
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Механическая работа. Механическая энергия. Закон сохранения механической энергии"
            "field_branch_order" => "4"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1206
              #items: array:1 [
                0 => App\Models\Term {#1203
                  #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" => "17"
            "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 {#1205
              #items: array:1 [
                0 => App\Models\Book {#1049}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1204
              #items: array:1 [
                0 => App\Models\Branch {#1045}
              ]
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1434833
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Механическая работа. Механическая энергия. Закон сохранения механической энергии"
            "field_branch_order" => "4"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1206}
            "field_page_start" => "17"
            "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 {#1205}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1204}
          ]
          #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 {#1207
          #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" => 1434834
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Общее определение механической работы. Мощность"
            "field_branch_order" => "25"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1211
              #items: array:1 [
                0 => App\Models\Term {#1208
                  #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" => "17"
            "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 {#1210
              #items: array:1 [
                0 => App\Models\Book {#1049}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1287
              #items: array:1 [
                0 => App\Models\Branch {#1209
                  #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" => 1434833
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Механическая работа. Механическая энергия. Закон сохранения механической энергии"
                    "field_branch_order" => "4"
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1213
                      #items: array:1 [
                        0 => App\Models\Term {#1212
                          #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 [ …7]
                          #original: array:7 [ …7]
                          #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_page_start" => "17"
                    "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 {#1214
                      #items: array:1 [
                        0 => App\Models\Book {#1215
                          #connection: "mysql"
                          #table: "books"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:50 [ …50]
                          #original: array:50 [ …50]
                          #changes: []
                          #casts: []
                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                           …6
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1247
                      #items: array:1 [
                        0 => App\Models\Branch {#1248 …30}
                      ]
                      #escapeWhenCastingToString: false
                    }
                  ]
                  #original: array:24 [
                    "id" => 1434833
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Механическая работа. Механическая энергия. Закон сохранения механической энергии"
                    "field_branch_order" => "4"
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1213}
                    "field_page_start" => "17"
                    "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 {#1214}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1247}
                  ]
                  #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" => 1434834
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Общее определение механической работы. Мощность"
            "field_branch_order" => "25"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1211}
            "field_page_start" => "17"
            "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 {#1210}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1287}
          ]
          #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 {#1177
      #items: array:2 [
        0 => App\Models\Element {#1195
          #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" => 1698452
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1149
              #items: array:1 [
                0 => App\Models\Edition {#1113
                  #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 {#1150
                      #items: array:1 [
                        0 => App\Models\Term {#1186 …30}
                      ]
                      #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 {#1153
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1154
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_process_formula" => "katex"
                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1184
                      #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 {#1150}
                    "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 {#1153}
                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1154}
                    "field_process_formula" => "katex"
                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1184}
                    "field_content_source" => null
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
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            "text" => "<p><strong>10.</strong> На движущееся поступательно по горизонтальной шероховатой дороге тело массой $m = 1\text{ кг}$ действует постоянная сила $\vec{F}$ (рис. 8). Коэффициент трения тела о дорогу $\mu = 0.3$, $|\vec{F}|=6\text{ Н}$, угол между направлениями силы и перемещения $\alpha = 30^\circ$. Определите работы каждой действующей силы и суммы всех сил при перемещении тела, равном по модулю $|\Delta\vec{r}|=1\text{ м}$. Полученные результаты сопоставьте с результатами задачи 5. В каком из случаев брусок будет скользить с большим по модулю ускорением?</p><p>Рис. 8</p><p><em>Решение.</em></p><p><em>Ответ:</em> ___________.</p>"
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            "text" => "<p><strong>Дано:</strong></p><p> $m = 1 \text{ кг}$ <br> $|\vec{F}| = F = 6 \text{ Н}$ <br> $\mu = 0.3$ <br> $\alpha = 30^\circ$ <br> $|\Delta\vec{r}| = s = 1 \text{ м}$ <br> $g \approx 10 \text{ м/с}^2$ (принимаем ускорение свободного падения равным 10 м/с²)</p><p>Все данные уже представлены в системе СИ.</p><p><strong>Найти:</strong></p><p> $A_F$, $A_g$, $A_N$, $A_{тр}$ - работы каждой из сил;<br> $A_{общ}$ - работу суммы всех сил;<br> Сравнить ускорения $a$ (в данном случае) и $a'$ (в случае, когда $\vec{F}$ направлена горизонтально).</p><p><strong>Решение:</strong></p><p>На тело действуют четыре силы: приложенная сила $\vec{F}$, сила тяжести $m\vec{g}$, сила нормальной реакции опоры $\vec{N}$ и сила трения скольжения $\vec{F}_{тр}$. Работа силы вычисляется по формуле $A = |\vec{F}| \cdot |\vec{s}| \cdot \cos{\beta}$, где $\beta$ — угол между вектором силы и вектором перемещения.</p><p><strong>Работы каждой действующей силы</strong></p><p>Работа приложенной силы $\vec{F}$:<br>Угол между силой $\vec{F}$ и перемещением $s$ равен $\alpha$.<br>$A_F = F \cdot s \cdot \cos{\alpha} = 6 \text{ Н} \cdot 1 \text{ м} \cdot \cos{30^\circ} = 6 \cdot \frac{\sqrt{3}}{2} = 3\sqrt{3} \approx 5,2 \text{ Дж}$.<br><strong>Ответ:</strong> $A_F \approx 5,2 \text{ Дж}$.</p><p>Работа силы тяжести $m\vec{g}$:<br>Сила тяжести перпендикулярна перемещению ($\beta = 90^\circ$).<br>$A_g = mgs \cdot \cos{90^\circ} = 0$.<br><strong>Ответ:</strong> $A_g = 0 \text{ Дж}$.</p><p>Работа силы реакции опоры $\vec{N}$:<br>Сила реакции опоры перпендикулярна перемещению ($\beta = 90^\circ$).<br>$A_N = Ns \cdot \cos{90^\circ} = 0$.<br><strong>Ответ:</strong> $A_N = 0 \text{ Дж}$.</p><p>Работа силы трения $\vec{F}_{тр}$:<br>Сила трения направлена противоположно перемещению ($\beta = 180^\circ$). Ее модуль $F_{тр} = \mu N$. Найдем силу реакции опоры $N$ из второго закона Ньютона в проекции на вертикальную ось OY:<br>$\sum F_y = N + F\sin{\alpha} - mg = 0 \implies N = mg - F\sin{\alpha}$<br>$N = 1 \text{ кг} \cdot 10 \text{ м/с}^2 - 6 \text{ Н} \cdot \sin{30^\circ} = 10 - 6 \cdot 0,5 = 7 \text{ Н}$.<br>Тогда сила трения: $F_{тр} = \mu N = 0,3 \cdot 7 \text{ Н} = 2,1 \text{ Н}$.<br>Работа силы трения: $A_{тр} = F_{тр} \cdot s \cdot \cos{180^\circ} = 2,1 \cdot 1 \cdot (-1) = -2,1 \text{ Дж}$.<br><strong>Ответ:</strong> $A_{тр} = -2,1 \text{ Дж}$.</p><p><strong>Работа суммы всех сил</strong></p><p>Работа суммы всех сил (равнодействующей) равна алгебраической сумме работ отдельных сил.<br>$A_{общ} = A_F + A_g + A_N + A_{тр} = 5,2 + 0 + 0 + (-2,1) = 3,1 \text{ Дж}$.<br><strong>Ответ:</strong> $A_{общ} = 3,1 \text{ Дж}$.</p><p><strong>Сравнение ускорений</strong></p><p>Сравним ускорение в данном случае ($a$) с ускорением в гипотетической задаче 5 ($a'$), где сила $\vec{F}$ приложена горизонтально ($\alpha=0$).<br>Ускорение в данном случае ($\alpha = 30^\circ$):<br>Из второго закона Ньютона в проекции на горизонтальную ось OX:<br>$ma = F\cos{\alpha} - F_{тр} \implies a = \frac{F\cos{\alpha} - F_{тр}}{m}$<br>$a = \frac{6 \cdot \cos{30^\circ} - 2,1}{1} \approx \frac{5,2 - 2,1}{1} = 3,1 \text{ м/с}^2$.<br>Ускорение при горизонтальной силе ($\alpha' = 0^\circ$):<br>Сила реакции опоры: $N' = mg = 1 \cdot 10 = 10 \text{ Н}$.<br>Сила трения: $F'_{тр} = \mu N' = 0,3 \cdot 10 = 3 \text{ Н}$.<br>Ускорение: $a' = \frac{F - F'_{тр}}{m} = \frac{6 - 3}{1} = 3 \text{ м/с}^2$.<br>Сравнивая полученные значения, видим, что $a &gt; a'$. Ускорение больше в случае, когда сила приложена под углом. Это объясняется тем, что вертикальная составляющая силы $\vec{F}$ уменьшает силу нормальной реакции опоры и, как следствие, силу трения. В данном случае уменьшение силы трения ($3 \text{ Н} - 2,1 \text{ Н} = 0,9 \text{ Н}$) оказалось больше, чем уменьшение горизонтальной составляющей движущей силы ($\approx 6 \text{ Н} - 5,2 \text{ Н} = 0,8 \text{ Н}$), что привело к увеличению равнодействующей силы.<br><strong>Ответ:</strong> Брусок будет скользить с большим по модулю ускорением в случае, когда сила приложена под углом $30^\circ$ к горизонту.</p>"
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            "text" => "<p><strong>Дано:</strong></p><p> $m = 1 \text{ кг}$ <br> $|\vec{F}| = F = 6 \text{ Н}$ <br> $\mu = 0.3$ <br> $\alpha = 30^\circ$ <br> $|\Delta\vec{r}| = s = 1 \text{ м}$ <br> $g \approx 10 \text{ м/с}^2$ (принимаем ускорение свободного падения равным 10 м/с²)</p><p>Все данные уже представлены в системе СИ.</p><p><strong>Найти:</strong></p><p> $A_F$, $A_g$, $A_N$, $A_{тр}$ - работы каждой из сил;<br> $A_{общ}$ - работу суммы всех сил;<br> Сравнить ускорения $a$ (в данном случае) и $a'$ (в случае, когда $\vec{F}$ направлена горизонтально).</p><p><strong>Решение:</strong></p><p>На тело действуют четыре силы: приложенная сила $\vec{F}$, сила тяжести $m\vec{g}$, сила нормальной реакции опоры $\vec{N}$ и сила трения скольжения $\vec{F}_{тр}$. Работа силы вычисляется по формуле $A = |\vec{F}| \cdot |\vec{s}| \cdot \cos{\beta}$, где $\beta$ — угол между вектором силы и вектором перемещения.</p><p><strong>Работы каждой действующей силы</strong></p><p>Работа приложенной силы $\vec{F}$:<br>Угол между силой $\vec{F}$ и перемещением $s$ равен $\alpha$.<br>$A_F = F \cdot s \cdot \cos{\alpha} = 6 \text{ Н} \cdot 1 \text{ м} \cdot \cos{30^\circ} = 6 \cdot \frac{\sqrt{3}}{2} = 3\sqrt{3} \approx 5,2 \text{ Дж}$.<br><strong>Ответ:</strong> $A_F \approx 5,2 \text{ Дж}$.</p><p>Работа силы тяжести $m\vec{g}$:<br>Сила тяжести перпендикулярна перемещению ($\beta = 90^\circ$).<br>$A_g = mgs \cdot \cos{90^\circ} = 0$.<br><strong>Ответ:</strong> $A_g = 0 \text{ Дж}$.</p><p>Работа силы реакции опоры $\vec{N}$:<br>Сила реакции опоры перпендикулярна перемещению ($\beta = 90^\circ$).<br>$A_N = Ns \cdot \cos{90^\circ} = 0$.<br><strong>Ответ:</strong> $A_N = 0 \text{ Дж}$.</p><p>Работа силы трения $\vec{F}_{тр}$:<br>Сила трения направлена противоположно перемещению ($\beta = 180^\circ$). Ее модуль $F_{тр} = \mu N$. Найдем силу реакции опоры $N$ из второго закона Ньютона в проекции на вертикальную ось OY:<br>$\sum F_y = N + F\sin{\alpha} - mg = 0 \implies N = mg - F\sin{\alpha}$<br>$N = 1 \text{ кг} \cdot 10 \text{ м/с}^2 - 6 \text{ Н} \cdot \sin{30^\circ} = 10 - 6 \cdot 0,5 = 7 \text{ Н}$.<br>Тогда сила трения: $F_{тр} = \mu N = 0,3 \cdot 7 \text{ Н} = 2,1 \text{ Н}$.<br>Работа силы трения: $A_{тр} = F_{тр} \cdot s \cdot \cos{180^\circ} = 2,1 \cdot 1 \cdot (-1) = -2,1 \text{ Дж}$.<br><strong>Ответ:</strong> $A_{тр} = -2,1 \text{ Дж}$.</p><p><strong>Работа суммы всех сил</strong></p><p>Работа суммы всех сил (равнодействующей) равна алгебраической сумме работ отдельных сил.<br>$A_{общ} = A_F + A_g + A_N + A_{тр} = 5,2 + 0 + 0 + (-2,1) = 3,1 \text{ Дж}$.<br><strong>Ответ:</strong> $A_{общ} = 3,1 \text{ Дж}$.</p><p><strong>Сравнение ускорений</strong></p><p>Сравним ускорение в данном случае ($a$) с ускорением в гипотетической задаче 5 ($a'$), где сила $\vec{F}$ приложена горизонтально ($\alpha=0$).<br>Ускорение в данном случае ($\alpha = 30^\circ$):<br>Из второго закона Ньютона в проекции на горизонтальную ось OX:<br>$ma = F\cos{\alpha} - F_{тр} \implies a = \frac{F\cos{\alpha} - F_{тр}}{m}$<br>$a = \frac{6 \cdot \cos{30^\circ} - 2,1}{1} \approx \frac{5,2 - 2,1}{1} = 3,1 \text{ м/с}^2$.<br>Ускорение при горизонтальной силе ($\alpha' = 0^\circ$):<br>Сила реакции опоры: $N' = mg = 1 \cdot 10 = 10 \text{ Н}$.<br>Сила трения: $F'_{тр} = \mu N' = 0,3 \cdot 10 = 3 \text{ Н}$.<br>Ускорение: $a' = \frac{F - F'_{тр}}{m} = \frac{6 - 3}{1} = 3 \text{ м/с}^2$.<br>Сравнивая полученные значения, видим, что $a &gt; a'$. Ускорение больше в случае, когда сила приложена под углом. Это объясняется тем, что вертикальная составляющая силы $\vec{F}$ уменьшает силу нормальной реакции опоры и, как следствие, силу трения. В данном случае уменьшение силы трения ($3 \text{ Н} - 2,1 \text{ Н} = 0,9 \text{ Н}$) оказалось больше, чем уменьшение горизонтальной составляющей движущей силы ($\approx 6 \text{ Н} - 5,2 \text{ Н} = 0,8 \text{ Н}$), что привело к увеличению равнодействующей силы.<br><strong>Ответ:</strong> Брусок будет скользить с большим по модулю ускорением в случае, когда сила приложена под углом $30^\circ$ к горизонту.</p>"
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№10 (с. 20)
Условие. №10 (с. 20)
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 20, номер 10, Условие

10. На движущееся поступательно по горизонтальной шероховатой дороге тело массой $m = 1\text{ кг}$ действует постоянная сила $\vec{F}$ (рис. 8). Коэффициент трения тела о дорогу $\mu = 0.3$, $|\vec{F}|=6\text{ Н}$, угол между направлениями силы и перемещения $\alpha = 30^\circ$. Определите работы каждой действующей силы и суммы всех сил при перемещении тела, равном по модулю $|\Delta\vec{r}|=1\text{ м}$. Полученные результаты сопоставьте с результатами задачи 5. В каком из случаев брусок будет скользить с большим по модулю ускорением?

Рис. 8

Решение.

Ответ: ___________.

Решение. №10 (с. 20)

Дано:

$m = 1 \text{ кг}$
$|\vec{F}| = F = 6 \text{ Н}$
$\mu = 0.3$
$\alpha = 30^\circ$
$|\Delta\vec{r}| = s = 1 \text{ м}$
$g \approx 10 \text{ м/с}^2$ (принимаем ускорение свободного падения равным 10 м/с²)

Все данные уже представлены в системе СИ.

Найти:

$A_F$, $A_g$, $A_N$, $A_{тр}$ - работы каждой из сил;
$A_{общ}$ - работу суммы всех сил;
Сравнить ускорения $a$ (в данном случае) и $a'$ (в случае, когда $\vec{F}$ направлена горизонтально).

Решение:

На тело действуют четыре силы: приложенная сила $\vec{F}$, сила тяжести $m\vec{g}$, сила нормальной реакции опоры $\vec{N}$ и сила трения скольжения $\vec{F}_{тр}$. Работа силы вычисляется по формуле $A = |\vec{F}| \cdot |\vec{s}| \cdot \cos{\beta}$, где $\beta$ — угол между вектором силы и вектором перемещения.

Работы каждой действующей силы

Работа приложенной силы $\vec{F}$:
Угол между силой $\vec{F}$ и перемещением $s$ равен $\alpha$.
$A_F = F \cdot s \cdot \cos{\alpha} = 6 \text{ Н} \cdot 1 \text{ м} \cdot \cos{30^\circ} = 6 \cdot \frac{\sqrt{3}}{2} = 3\sqrt{3} \approx 5,2 \text{ Дж}$.
Ответ: $A_F \approx 5,2 \text{ Дж}$.

Работа силы тяжести $m\vec{g}$:
Сила тяжести перпендикулярна перемещению ($\beta = 90^\circ$).
$A_g = mgs \cdot \cos{90^\circ} = 0$.
Ответ: $A_g = 0 \text{ Дж}$.

Работа силы реакции опоры $\vec{N}$:
Сила реакции опоры перпендикулярна перемещению ($\beta = 90^\circ$).
$A_N = Ns \cdot \cos{90^\circ} = 0$.
Ответ: $A_N = 0 \text{ Дж}$.

Работа силы трения $\vec{F}_{тр}$:
Сила трения направлена противоположно перемещению ($\beta = 180^\circ$). Ее модуль $F_{тр} = \mu N$. Найдем силу реакции опоры $N$ из второго закона Ньютона в проекции на вертикальную ось OY:
$\sum F_y = N + F\sin{\alpha} - mg = 0 \implies N = mg - F\sin{\alpha}$
$N = 1 \text{ кг} \cdot 10 \text{ м/с}^2 - 6 \text{ Н} \cdot \sin{30^\circ} = 10 - 6 \cdot 0,5 = 7 \text{ Н}$.
Тогда сила трения: $F_{тр} = \mu N = 0,3 \cdot 7 \text{ Н} = 2,1 \text{ Н}$.
Работа силы трения: $A_{тр} = F_{тр} \cdot s \cdot \cos{180^\circ} = 2,1 \cdot 1 \cdot (-1) = -2,1 \text{ Дж}$.
Ответ: $A_{тр} = -2,1 \text{ Дж}$.

Работа суммы всех сил

Работа суммы всех сил (равнодействующей) равна алгебраической сумме работ отдельных сил.
$A_{общ} = A_F + A_g + A_N + A_{тр} = 5,2 + 0 + 0 + (-2,1) = 3,1 \text{ Дж}$.
Ответ: $A_{общ} = 3,1 \text{ Дж}$.

Сравнение ускорений

Сравним ускорение в данном случае ($a$) с ускорением в гипотетической задаче 5 ($a'$), где сила $\vec{F}$ приложена горизонтально ($\alpha=0$).
Ускорение в данном случае ($\alpha = 30^\circ$):
Из второго закона Ньютона в проекции на горизонтальную ось OX:
$ma = F\cos{\alpha} - F_{тр} \implies a = \frac{F\cos{\alpha} - F_{тр}}{m}$
$a = \frac{6 \cdot \cos{30^\circ} - 2,1}{1} \approx \frac{5,2 - 2,1}{1} = 3,1 \text{ м/с}^2$.
Ускорение при горизонтальной силе ($\alpha' = 0^\circ$):
Сила реакции опоры: $N' = mg = 1 \cdot 10 = 10 \text{ Н}$.
Сила трения: $F'_{тр} = \mu N' = 0,3 \cdot 10 = 3 \text{ Н}$.
Ускорение: $a' = \frac{F - F'_{тр}}{m} = \frac{6 - 3}{1} = 3 \text{ м/с}^2$.
Сравнивая полученные значения, видим, что $a > a'$. Ускорение больше в случае, когда сила приложена под углом. Это объясняется тем, что вертикальная составляющая силы $\vec{F}$ уменьшает силу нормальной реакции опоры и, как следствие, силу трения. В данном случае уменьшение силы трения ($3 \text{ Н} - 2,1 \text{ Н} = 0,9 \text{ Н}$) оказалось больше, чем уменьшение горизонтальной составляющей движущей силы ($\approx 6 \text{ Н} - 5,2 \text{ Н} = 0,8 \text{ Н}$), что привело к увеличению равнодействующей силы.
Ответ: Брусок будет скользить с большим по модулю ускорением в случае, когда сила приложена под углом $30^\circ$ к горизонту.

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