Номер 9, страница 61 - гдз по физике 9 класс учебник Изергин

Физика, 9 класс Учебник, автор: Изергин Эдуард Тимофеевич, издательство Русское слово, Москва, 2019

Авторы: Изергин Э. Т.

Тип: Учебник

Серия: инновационная школа

Издательство: Русское слово

Год издания: 2019 - 2026

Цвет обложки: синий

ISBN: 978-5-533-01069-6

Глава II. Динамика. Параграф 13. Закон сохранения энергии - номер 9, страница 61.

App\Models\Task {#1024 // resources/views/models/task/default.blade.php
  #connection: "mysql"
  #table: "tasks"
  #primaryKey: "id"
  #keyType: "int"
  +incrementing: true
  #with: []
  #withCount: []
  +preventsLazyLoading: false
  #perPage: 15
  +exists: true
  +wasRecentlyCreated: false
  #escapeWhenCastingToString: false
  #attributes: array:24 [
    "id" => 1439715
    "created_at" => "2026-04-10 13:58:26"
    "updated_at" => null
    "field_page_start" => "61"
    "field_page_end" => null
    "field_url" => "/9-klass/fizika/izergin-uchebnik/13-9"
    "field_display_title" => "9"
    "field_outside_task" => null
    "field_task_type" => Illuminate\Database\Eloquent\Collection {#331
      #items: array:1 [
        0 => App\Models\Term {#1029
          #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" => 26
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "name" => "номер"
            "field_cases" => array:6 [
              "field_accusative_case" => "номер"
              "field_creative_case" => "номером"
              "field_dative_case" => "номеру"
              "field_genitive_case" => "номера"
              "field_nominative_case" => "номер"
              "field_prepositional_case" => "номере"
            ]
            "field_short_name" => ""
          ]
          #original: array:6 [
            "id" => 26
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "name" => "номер"
            "field_cases" => array:6 [
              "field_accusative_case" => "номер"
              "field_creative_case" => "номером"
              "field_dative_case" => "номеру"
              "field_genitive_case" => "номера"
              "field_nominative_case" => "номер"
              "field_prepositional_case" => "номере"
            ]
            "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_metatags_title" => null
    "field_metatags_description" => null
    "field_h1" => null
    "field_description_top" => null
    "field_description_bottom" => null
    "field_match" => null
    "breadcrumbs" => []
    "edition_groups" => Illuminate\Database\Eloquent\Collection {#1026
      #items: []
      #escapeWhenCastingToString: false
    }
    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#342
      #items: array:1 [
        0 => App\Models\Branch {#1023
          #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" => 1439551
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Динамика"
            "field_branch_order" => "II"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#333
              #items: array:1 [
                0 => App\Models\Term {#1033
                  #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: []
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                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "30"
            "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 {#1030
              #items: array:1 [
                0 => App\Models\Book {#1032
                  #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 [
                    "id" => 4169
                    "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 {#1034
                      #items: array:1 [
                        0 => App\Models\Term {#1035
                          #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" => 6493
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Физика"
                            "field_abbreviated_name" => null
                            "field_cases" => array:6 [
                              "field_accusative_case" => "физику"
                              "field_creative_case" => "физикой"
                              "field_dative_case" => "физике"
                              "field_genitive_case" => "физики"
                              "field_nominative_case" => "физика"
                              "field_prepositional_case" => "физике"
                            ]
                            "field_foreign_lang_name" => null
                            "field_short_name" => null
                            "field_subject_type" => "technical_subject"
                            "field_translit" => "fizika"
                          ]
                          #original: array:10 [
                            "id" => 6493
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Физика"
                            "field_abbreviated_name" => null
                            "field_cases" => array:6 [
                              "field_accusative_case" => "физику"
                              "field_creative_case" => "физикой"
                              "field_dative_case" => "физике"
                              "field_genitive_case" => "физики"
                              "field_nominative_case" => "физика"
                              "field_prepositional_case" => "физике"
                            ]
                            "field_foreign_lang_name" => null
                            "field_short_name" => null
                            "field_subject_type" => "technical_subject"
                            "field_translit" => "fizika"
                          ]
                          #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_class" => Illuminate\Database\Eloquent\Collection {#1036
                      #items: array:1 [
                        0 => App\Models\Term {#1037
                          #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" => 5458
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "9"
                            "field_cases" => array:6 [
                              "field_accusative_case" => "девятый"
                              "field_creative_case" => "девятым"
                              "field_dative_case" => "девятому"
                              "field_genitive_case" => "девятого"
                              "field_nominative_case" => "девятый"
                              "field_prepositional_case" => "девятом"
                            ]
                            "field_translit" => "devjatyj"
                          ]
                          #original: array:6 [
                            "id" => 5458
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "9"
                            "field_cases" => array:6 [
                              "field_accusative_case" => "девятый"
                              "field_creative_case" => "девятым"
                              "field_dative_case" => "девятому"
                              "field_genitive_case" => "девятого"
                              "field_nominative_case" => "девятый"
                              "field_prepositional_case" => "девятом"
                            ]
                            "field_translit" => "devjatyj"
                          ]
                          #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_publisher" => Illuminate\Database\Eloquent\Collection {#1038
                      #items: array:1 [
                        0 => App\Models\Term {#1039
                          #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" => 5176
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Русское слово"
                            "field_cases" => null
                            "field_translit" => "russkoe slovo"
                          ]
                          #original: array:6 [
                            "id" => 5176
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Русское слово"
                            "field_cases" => null
                            "field_translit" => "russkoe slovo"
                          ]
                          #changes: []
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                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
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                          #relations: []
                          #touches: []
                          +timestamps: true
                          +usesUniqueIds: false
                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_author" => Illuminate\Database\Eloquent\Collection {#1040
                      #items: array:1 [
                        0 => App\Models\Term {#1041
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:12 [
                            "id" => 4491
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Изергин"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Эдуард"
                            "field_patronymic" => "Тимофеевич"
                            "field_surname_rp" => null
                          ]
                          #original: array:12 [
                            "id" => 4491
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Изергин"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Эдуард"
                            "field_patronymic" => "Тимофеевич"
                            "field_surname_rp" => 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_author_foreign" => Illuminate\Database\Eloquent\Collection {#1042
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1043
                      #items: array:1 [
                        0 => App\Models\Term {#1044
                          #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" => 6671
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Учебник"
                            "field_book_type_foreign" => null
                            "field_cases" => array:6 [
                              "field_accusative_case" => "учебник"
                              "field_creative_case" => "учебником"
                              "field_dative_case" => "учебнику"
                              "field_genitive_case" => "учебника"
                              "field_nominative_case" => "учебник"
                              "field_prepositional_case" => "учебнике"
                            ]
                            "field_plural_form" => null
                            "field_short_name" => null
                            "field_short_name_foreign" => null
                            "field_translit" => "uchebnik"
                          ]
                          #original: array:10 [
                            "id" => 6671
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Учебник"
                            "field_book_type_foreign" => null
                            "field_cases" => array:6 [
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                              "field_dative_case" => "учебнику"
                              "field_genitive_case" => "учебника"
                              "field_nominative_case" => "учебник"
                              "field_prepositional_case" => "учебнике"
                            ]
                            "field_plural_form" => null
                            "field_short_name" => null
                            "field_short_name_foreign" => null
                            "field_translit" => "uchebnik"
                          ]
                          #changes: []
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                          #attributeCastCache: []
                          #dateFormat: null
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                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1045
                      #items: array:1 [
                        0 => App\Models\Term {#1046
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
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                          #perPage: 15
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                          #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
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                              "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"
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                              "field_nominative_case" => null
                              "field_prepositional_case" => null
                            ]
                            "field_translit" => "rossiya"
                          ]
                          #changes: []
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                          #attributeCastCache: []
                          #dateFormat: null
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                          #dispatchesEvents: []
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                          #touches: []
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                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1047
                      #items: array:1 [
                        0 => App\Models\Term {#1048
                          #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" => 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 [
                              "field_accusative_case" => null
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                              "field_nominative_case" => null
                              "field_prepositional_case" => null
                            ]
                            "field_translit" => "moskva"
                          ]
                          #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_series" => Illuminate\Database\Eloquent\Collection {#1049
                      #items: array:1 [
                        0 => App\Models\Term {#1050
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:8 [
                            "id" => 4715
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "инновационная школа"
                            "field_cases" => null
                            "field_foreign_lang_series" => null
                            "field_transcription_eng" => null
                            "field_translit" => "innovacionnaya shkola"
                          ]
                          #original: array:8 [
                            "id" => 4715
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "инновационная школа"
                            "field_cases" => null
                            "field_foreign_lang_series" => null
                            "field_transcription_eng" => null
                            "field_translit" => "innovacionnaya shkola"
                          ]
                          #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_umk" => Illuminate\Database\Eloquent\Collection {#1051
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1052
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1053
                      #items: array:1 [
                        0 => App\Models\Term {#1054
                          #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
                              "field_dative_case" => null
                              "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 [
                              "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_color" => null
                            "field_end_year" => "2022"
                            "field_start_year" => "2019"
                            "field_translit" => "fgos-old"
                            "field_type" => 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_publication_number" => null
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1055
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1056
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_under_the_edition_degree" => null
                    "field_cover_description" => null
                    "field_publication_year" => "2019"
                    "field_publication_year_until" => null
                    "field_part" => ""
                    "field_part_writing" => ""
                    "field_second_foreign_language" => null
                    "field_for_whom" => "Учебник для 9 класса общеобразовательных организаций"
                    "field_allowed" => null
                    "field_reserve_field" => null
                    "field_link_to_source" => null
                    "field_tasks_count" => "388"
                    "field_priority" => null
                    "field_default_folder" => "/fizika_09/izergin-u/"
                    "field_isbn" => "978-5-533-01069-6"
                    "field_cover" => array:1 [
                      0 => "/media/fizika_09/izergin-u/covers/cover1.webp?ts=1759162386"
                    ]
                    "field_cover_alts" => array:1 [
                      0 => ""
                    ]
                    "field_covers" => array:1 [
                      0 => array:4 [
                        "path" => "/media/fizika_09/izergin-u/covers/cover1.webp?ts=1759162386"
                        "alt" => ""
                        "width" => "1881"
                        "height" => "2502"
                      ]
                    ]
                    "field_popular_book" => "0"
                    "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1057
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1058
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1059
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_url" => "/9-klass/fizika/izergin-uchebnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1060
                      #items: array:1 [
                        0 => App\Models\Term {#1061
                          #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 [
                              "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"
                          ]
                          #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_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "breadcrumbs" => array:3 [
                      "class" => 380
                      "subject" => 556
                      "class_subject" => 493
                    ]
                  ]
                  #original: array:50 [
                    "id" => 4169
                    "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 {#1034}
                    "field_class" => Illuminate\Database\Eloquent\Collection {#1036}
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1038}
                    "field_author" => Illuminate\Database\Eloquent\Collection {#1040}
                    "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1042}
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1043}
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1045}
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1047}
                    "field_series" => Illuminate\Database\Eloquent\Collection {#1049}
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1051}
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1052}
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1053}
                    "field_publication_number" => null
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1055}
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1056}
                    "field_under_the_edition_degree" => null
                    "field_cover_description" => null
                    "field_publication_year" => "2019"
                    "field_publication_year_until" => null
                    "field_part" => ""
                    "field_part_writing" => ""
                    "field_second_foreign_language" => null
                    "field_for_whom" => "Учебник для 9 класса общеобразовательных организаций"
                    "field_allowed" => null
                    "field_reserve_field" => null
                    "field_link_to_source" => null
                    "field_tasks_count" => "388"
                    "field_priority" => null
                    "field_default_folder" => "/fizika_09/izergin-u/"
                    "field_isbn" => "978-5-533-01069-6"
                    "field_cover" => array:1 [
                      0 => "/media/fizika_09/izergin-u/covers/cover1.webp?ts=1759162386"
                    ]
                    "field_cover_alts" => array:1 [
                      0 => ""
                    ]
                    "field_covers" => array:1 [
                      0 => array:4 [
                        "path" => "/media/fizika_09/izergin-u/covers/cover1.webp?ts=1759162386"
                        "alt" => ""
                        "width" => "1881"
                        "height" => "2502"
                      ]
                    ]
                    "field_popular_book" => "0"
                    "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1057}
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1058}
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1059}
                    "field_url" => "/9-klass/fizika/izergin-uchebnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1060}
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "breadcrumbs" => array:3 [
                      "class" => 380
                      "subject" => 556
                      "class_subject" => 493
                    ]
                  ]
                  #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
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1062
              #items: []
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1439551
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Динамика"
            "field_branch_order" => "II"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#333}
            "field_page_start" => "30"
            "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 {#1030}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1062}
          ]
          #changes: []
          #casts: []
          #classCastCache: []
          #attributeCastCache: []
          #dateFormat: null
          #appends: []
          #dispatchesEvents: []
          #observables: []
          #relations: []
          #touches: []
          +timestamps: true
          +usesUniqueIds: false
          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
      ]
      #escapeWhenCastingToString: false
    }
    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1063
      #items: array:2 [
        0 => App\Models\Branch {#1023}
        1 => App\Models\Branch {#1064
          #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" => 1439558
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Закон сохранения энергии"
            "field_branch_order" => "13"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1065
              #items: array:1 [
                0 => App\Models\Term {#1066
                  #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" => "57"
            "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 {#1067
              #items: array:1 [
                0 => App\Models\Book {#1032}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1068
              #items: array:1 [
                0 => App\Models\Branch {#1069
                  #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" => 1439551
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Динамика"
                    "field_branch_order" => "II"
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1070
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "field_page_start" => "30"
                    "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 {#1072
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1102
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                  ]
                  #original: array:24 [
                    "id" => 1439551
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Динамика"
                    "field_branch_order" => "II"
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1070}
                    "field_page_start" => "30"
                    "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
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                    "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 {#1072}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1102}
                  ]
                  #changes: []
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                  #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" => 1439558
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Закон сохранения энергии"
            "field_branch_order" => "13"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1065}
            "field_page_start" => "57"
            "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 {#1067}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1068}
          ]
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    "content" => Illuminate\Database\Eloquent\Collection {#1103
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            "created_at" => "2026-04-10 13:58:26"
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            "edition" => Illuminate\Database\Eloquent\Collection {#1105
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                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1107
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                    "field_content_type" => "free"
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                    "field_solution_author" => "Автор"
                    "field_moderator" => "stas"
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                    "field_responsible" => Illuminate\Database\Eloquent\Collection {#1109
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                    "field_responsible" => Illuminate\Database\Eloquent\Collection {#1109}
                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1110}
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            "task" => array:2 [
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            "text" => "<p><strong>9.</strong> Подвешенный на нити шарик отвели в сторону так, что он поднялся на высоту 20 см (рис. 61). Затем его выпустили из рук. Чему будет равна максимальная скорость движения шарика?</p><p><strong>Рис. 61.</strong> К заданию 9</p>"
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                "width" => "960"
                "height" => 335
                "path" => "/media/fizika_09/izergin-u/0-13/9-1.webp?ts=1759529221"
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                "width" => "609"
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            "id" => 1707273
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1105}
            "task" => array:2 [
              "refs" => "1439715"
              "type" => "task"
            ]
            "text" => "<p><strong>9.</strong> Подвешенный на нити шарик отвели в сторону так, что он поднялся на высоту 20 см (рис. 61). Затем его выпустили из рук. Чему будет равна максимальная скорость движения шарика?</p><p><strong>Рис. 61.</strong> К заданию 9</p>"
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                "width" => "609"
                "height" => 799
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            "created_at" => "2026-04-10 13:58:26"
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            "edition" => Illuminate\Database\Eloquent\Collection {#1113
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                    "created_at" => "2026-04-10 13:58:26"
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                    "title" => "Решение"
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                    "created_at" => "2026-04-10 13:58:26"
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            "text" => "<p><strong>Дано:</strong></p><p>$h = 20 \text{ см}$</p><p><br>$h = 0.2 \text{ м}$<br>$g \approx 10 \text{ м/с}^2$ (ускорение свободного падения)</p><p><strong>Найти:</strong></p><p>$v_{max}$ - ?</p><p><strong>Решение:</strong></p><p>Эта задача решается с помощью закона сохранения механической энергии. Когда шарик отвели в сторону на высоту $\text{h}$, он обладает потенциальной энергией, но его кинетическая энергия равна нулю, так как его отпускают из состояния покоя. Максимальная скорость будет в самой нижней точке траектории (в положении равновесия), где высота минимальна. Примем высоту в этой точке за нулевой уровень потенциальной энергии.</p><p><strong>1.</strong> Энергия в начальной точке (на высоте $\text{h}$):</p><p>Скорость $v_1 = 0$, поэтому кинетическая энергия $K_1 = 0$.</p><p>Потенциальная энергия $U_1 = mgh$, где $\text{m}$ - масса шарика.</p><p>Полная механическая энергия $E_1 = K_1 + U_1 = mgh$.</p><p><strong>2.</strong> Энергия в нижней точке (положении равновесия):</p><p>Высота равна нулю, поэтому потенциальная энергия $U_2 = 0$.</p><p>Скорость максимальна $v_2 = v_{max}$, поэтому кинетическая энергия $K_2 = \frac{mv_{max}^2}{2}$.</p><p>Полная механическая энергия $E_2 = K_2 + U_2 = \frac{mv_{max}^2}{2}$.</p><p><strong>3.</strong> По закону сохранения энергии (пренебрегая сопротивлением воздуха), полная механическая энергия системы сохраняется, то есть $E_1 = E_2$.</p><p>$mgh = \frac{mv_{max}^2}{2}$</p><p>Масса шарика $\text{m}$ сокращается в обеих частях уравнения:</p><p>$gh = \frac{v_{max}^2}{2}$</p><p>Отсюда выразим максимальную скорость $v_{max}$:</p><p>$v_{max}^2 = 2gh$</p><p>$v_{max} = \sqrt{2gh}$</p><p>Подставим числовые значения в систему СИ:</p><p>$v_{max} = \sqrt{2 \cdot 10 \text{ м/с}^2 \cdot 0.2 \text{ м}} = \sqrt{4 \text{ м}^2/\text{с}^2} = 2 \text{ м/с}$</p><p><strong>Ответ:</strong> максимальная скорость движения шарика будет равна 2 м/с.</p>"
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            "edition" => Illuminate\Database\Eloquent\Collection {#1113}
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            "text" => "<p><strong>Дано:</strong></p><p>$h = 20 \text{ см}$</p><p><br>$h = 0.2 \text{ м}$<br>$g \approx 10 \text{ м/с}^2$ (ускорение свободного падения)</p><p><strong>Найти:</strong></p><p>$v_{max}$ - ?</p><p><strong>Решение:</strong></p><p>Эта задача решается с помощью закона сохранения механической энергии. Когда шарик отвели в сторону на высоту $\text{h}$, он обладает потенциальной энергией, но его кинетическая энергия равна нулю, так как его отпускают из состояния покоя. Максимальная скорость будет в самой нижней точке траектории (в положении равновесия), где высота минимальна. Примем высоту в этой точке за нулевой уровень потенциальной энергии.</p><p><strong>1.</strong> Энергия в начальной точке (на высоте $\text{h}$):</p><p>Скорость $v_1 = 0$, поэтому кинетическая энергия $K_1 = 0$.</p><p>Потенциальная энергия $U_1 = mgh$, где $\text{m}$ - масса шарика.</p><p>Полная механическая энергия $E_1 = K_1 + U_1 = mgh$.</p><p><strong>2.</strong> Энергия в нижней точке (положении равновесия):</p><p>Высота равна нулю, поэтому потенциальная энергия $U_2 = 0$.</p><p>Скорость максимальна $v_2 = v_{max}$, поэтому кинетическая энергия $K_2 = \frac{mv_{max}^2}{2}$.</p><p>Полная механическая энергия $E_2 = K_2 + U_2 = \frac{mv_{max}^2}{2}$.</p><p><strong>3.</strong> По закону сохранения энергии (пренебрегая сопротивлением воздуха), полная механическая энергия системы сохраняется, то есть $E_1 = E_2$.</p><p>$mgh = \frac{mv_{max}^2}{2}$</p><p>Масса шарика $\text{m}$ сокращается в обеих частях уравнения:</p><p>$gh = \frac{v_{max}^2}{2}$</p><p>Отсюда выразим максимальную скорость $v_{max}$:</p><p>$v_{max}^2 = 2gh$</p><p>$v_{max} = \sqrt{2gh}$</p><p>Подставим числовые значения в систему СИ:</p><p>$v_{max} = \sqrt{2 \cdot 10 \text{ м/с}^2 \cdot 0.2 \text{ м}} = \sqrt{4 \text{ м}^2/\text{с}^2} = 2 \text{ м/с}$</p><p><strong>Ответ:</strong> максимальная скорость движения шарика будет равна 2 м/с.</p>"
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                    "field_url" => "/9-klass/fizika/izergin-uchebnik"
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                    "field_default_folder" => "/fizika_09/izergin-u/"
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                      0 => "/media/fizika_09/izergin-u/covers/cover1.webp?ts=1759162386"
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                      0 => ""
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                    "field_covers" => array:1 [
                      0 => array:4 [ …4]
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                    "field_url" => "/9-klass/fizika/izergin-uchebnik"
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                    ]
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                      0 => array:5 [ …5]
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                0 => App\Models\Task {#1169
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                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1173
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                      #escapeWhenCastingToString: false
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                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1208
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                      #escapeWhenCastingToString: false
                    }
                    "content" => Illuminate\Database\Eloquent\Collection {#1277
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                    "book" => Illuminate\Database\Eloquent\Collection {#1294
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                      #escapeWhenCastingToString: false
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                    "book" => Illuminate\Database\Eloquent\Collection {#1294}
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                    0 => "*"
                  ]
                }
                1 => App\Models\Task {#1295
                  #connection: "mysql"
                  #table: "tasks"
                  #primaryKey: "id"
                  #keyType: "int"
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                  #attributes: array:24 [
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                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1299
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                      #escapeWhenCastingToString: false
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                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1334
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                      #escapeWhenCastingToString: false
                    }
                    "content" => Illuminate\Database\Eloquent\Collection {#1403
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                    "book" => Illuminate\Database\Eloquent\Collection {#1420
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                      #escapeWhenCastingToString: false
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                    0 => "*"
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                }
                2 => App\Models\Task {#1421
                  #connection: "mysql"
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                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1422
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                      #escapeWhenCastingToString: false
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                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1425
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                      #escapeWhenCastingToString: false
                    }
                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1460
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                      #escapeWhenCastingToString: false
                    }
                    "content" => Illuminate\Database\Eloquent\Collection {#1500
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                      #escapeWhenCastingToString: false
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                    "next" => array:2 [
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                    "book" => Illuminate\Database\Eloquent\Collection {#1517
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                    "book" => Illuminate\Database\Eloquent\Collection {#1517}
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                    0 => "*"
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                }
                3 => App\Models\Task {#1518
                  #connection: "mysql"
                  #table: "tasks"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
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                  #perPage: 15
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                  #escapeWhenCastingToString: false
                  #attributes: array:24 [
                    "id" => 1439713
                    "created_at" => "2026-04-10 13:58:26"
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                    "field_url" => "/9-klass/fizika/izergin-uchebnik/13-7"
                    "field_display_title" => "7"
                    "field_outside_task" => null
                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1519 …2}
                    "field_metatags_title" => null
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                    "edition_groups" => Illuminate\Database\Eloquent\Collection {#1521 …2}
                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1522 …2}
                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1557 …2}
                    "content" => Illuminate\Database\Eloquent\Collection {#1597 …2}
                    "next" => array:2 [ …2]
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                    "book" => Illuminate\Database\Eloquent\Collection {#1614 …2}
                    "page" => array:2 [ …2]
                  ]
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                    "field_display_title" => "7"
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                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1519 …2}
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                    0 => "*"
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                }
                4 => App\Models\Task {#1615
                  #connection: "mysql"
                  #table: "tasks"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
                  #with: []
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                  #perPage: 15
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                  #escapeWhenCastingToString: false
                  #attributes: array:24 [
                    "id" => 1439714
                    "created_at" => "2026-04-10 13:58:26"
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                    "field_url" => "/9-klass/fizika/izergin-uchebnik/13-8"
                    "field_display_title" => "8"
                    "field_outside_task" => null
                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1616 …2}
                    "field_metatags_title" => null
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                    "edition_groups" => Illuminate\Database\Eloquent\Collection {#1618 …2}
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                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1654 …2}
                    "content" => Illuminate\Database\Eloquent\Collection {#1694 …2}
                    "next" => array:2 [ …2]
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                    "book" => Illuminate\Database\Eloquent\Collection {#1711 …2}
                    "page" => array:2 [ …2]
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                  #original: array:24 [
                    "id" => 1439714
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№9 (с. 61)
Условие. №9 (с. 61)
скриншот условия
Физика, 9 класс Учебник, автор: Изергин Эдуард Тимофеевич, издательство Русское слово, Москва, 2019, страница 61, номер 9, Условие
Физика, 9 класс Учебник, автор: Изергин Эдуард Тимофеевич, издательство Русское слово, Москва, 2019, страница 61, номер 9, Условие (продолжение 2)

9. Подвешенный на нити шарик отвели в сторону так, что он поднялся на высоту 20 см (рис. 61). Затем его выпустили из рук. Чему будет равна максимальная скорость движения шарика?

Рис. 61. К заданию 9

Решение. №9 (с. 61)

Дано:

$h = 20 \text{ см}$


$h = 0.2 \text{ м}$
$g \approx 10 \text{ м/с}^2$ (ускорение свободного падения)

Найти:

$v_{max}$ - ?

Решение:

Эта задача решается с помощью закона сохранения механической энергии. Когда шарик отвели в сторону на высоту $\text{h}$, он обладает потенциальной энергией, но его кинетическая энергия равна нулю, так как его отпускают из состояния покоя. Максимальная скорость будет в самой нижней точке траектории (в положении равновесия), где высота минимальна. Примем высоту в этой точке за нулевой уровень потенциальной энергии.

1. Энергия в начальной точке (на высоте $\text{h}$):

Скорость $v_1 = 0$, поэтому кинетическая энергия $K_1 = 0$.

Потенциальная энергия $U_1 = mgh$, где $\text{m}$ - масса шарика.

Полная механическая энергия $E_1 = K_1 + U_1 = mgh$.

2. Энергия в нижней точке (положении равновесия):

Высота равна нулю, поэтому потенциальная энергия $U_2 = 0$.

Скорость максимальна $v_2 = v_{max}$, поэтому кинетическая энергия $K_2 = \frac{mv_{max}^2}{2}$.

Полная механическая энергия $E_2 = K_2 + U_2 = \frac{mv_{max}^2}{2}$.

3. По закону сохранения энергии (пренебрегая сопротивлением воздуха), полная механическая энергия системы сохраняется, то есть $E_1 = E_2$.

$mgh = \frac{mv_{max}^2}{2}$

Масса шарика $\text{m}$ сокращается в обеих частях уравнения:

$gh = \frac{v_{max}^2}{2}$

Отсюда выразим максимальную скорость $v_{max}$:

$v_{max}^2 = 2gh$

$v_{max} = \sqrt{2gh}$

Подставим числовые значения в систему СИ:

$v_{max} = \sqrt{2 \cdot 10 \text{ м/с}^2 \cdot 0.2 \text{ м}} = \sqrt{4 \text{ м}^2/\text{с}^2} = 2 \text{ м/с}$

Ответ: максимальная скорость движения шарика будет равна 2 м/с.

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