Номер 40, страница 75 - гдз по физике 10-11 класс задачник Гельфгат, Генденштейн

Физика, 10-11 класс Задачник, авторы: Гельфгат Илья Маркович, Генденштейн Лев Элевич, Кирик Леонид Анатольевич, издательство Илекса, Москва, 2008, красного цвета

Авторы: Гельфгат И. М., Генденштейн Л. Э., Кирик Л. А.

Тип: Задачник

Издательство: Илекса

Год издания: 2008 - 2026

Уровень обучения: профильный

Цвет обложки: красный лупа, парень едет на велосипеде

ISBN: 978-5-89237-252-7

Механика. Законы сохранения в механике. 10. Импульс. Закон сохранения импульса. Олимпиадные задачи - номер 40, страница 75.

App\Models\Task {#1030 // resources/views/models/task/default.blade.php
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  #table: "tasks"
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              #items: array:1 [
                0 => App\Models\Book {#1040
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                    ]
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                            "name" => "11"
                            "field_cases" => array:6 [
                              "field_accusative_case" => "одиннадцатый"
                              "field_creative_case" => "одиннадцатым"
                              "field_dative_case" => "одиннадцатому"
                              "field_genitive_case" => "одинадцатого"
                              "field_nominative_case" => "одинадцатый"
                              "field_prepositional_case" => "одиннадцатом"
                            ]
                            "field_translit" => "odinadcatyj"
                          ]
                          #original: array:6 [
                            "id" => 5460
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "11"
                            "field_cases" => array:6 [
                              "field_accusative_case" => "одиннадцатый"
                              "field_creative_case" => "одиннадцатым"
                              "field_dative_case" => "одиннадцатому"
                              "field_genitive_case" => "одинадцатого"
                              "field_nominative_case" => "одинадцатый"
                              "field_prepositional_case" => "одиннадцатом"
                            ]
                            "field_translit" => "odinadcatyj"
                          ]
                          #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 {#1167
                      #items: array:1 [
                        0 => App\Models\Term {#1168
                          #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" => 5158
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Илекса"
                            "field_cases" => null
                            "field_translit" => "ileksa"
                          ]
                          #original: array:6 [
                            "id" => 5158
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Илекса"
                            "field_cases" => null
                            "field_translit" => "ileksa"
                          ]
                          #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" => Illuminate\Database\Eloquent\Collection {#1169
                      #items: array:3 [
                        0 => App\Models\Term {#1170
                          #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" => 4102
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Гельфгат"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Илья"
                            "field_patronymic" => "Маркович"
                            "field_surname_rp" => null
                          ]
                          #original: array:12 [
                            "id" => 4102
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Гельфгат"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Илья"
                            "field_patronymic" => "Маркович"
                            "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 => "*"
                          ]
                        }
                        1 => App\Models\Term {#1171
                          #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" => 4104
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Генденштейн"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Лев"
                            "field_patronymic" => "Элевич"
                            "field_surname_rp" => "Генденштейна"
                          ]
                          #original: array:12 [
                            "id" => 4104
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Генденштейн"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Лев"
                            "field_patronymic" => "Элевич"
                            "field_surname_rp" => "Генденштейна"
                          ]
                          #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\Term {#1172
                          #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" => 4583
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Кирик"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Леонид"
                            "field_patronymic" => "Анатольевич"
                            "field_surname_rp" => null
                          ]
                          #original: array:12 [
                            "id" => 4583
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Кирик"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Леонид"
                            "field_patronymic" => "Анатольевич"
                            "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 {#1173
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1174
                      #items: array:1 [
                        0 => App\Models\Term {#1175
                          #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" => 6518
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Задачник"
                            "field_book_type_foreign" => null
                            "field_cases" => array:6 [
                              "field_accusative_case" => "задачник"
                              "field_creative_case" => "задачником"
                              "field_dative_case" => "задачнику"
                              "field_genitive_case" => "задачника"
                              "field_nominative_case" => "задачник"
                              "field_prepositional_case" => "задачнике"
                            ]
                            "field_plural_form" => null
                            "field_short_name" => null
                            "field_short_name_foreign" => null
                            "field_translit" => "zadachnik"
                          ]
                          #original: array:10 [
                            "id" => 6518
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Задачник"
                            "field_book_type_foreign" => null
                            "field_cases" => array:6 [
                              "field_accusative_case" => "задачник"
                              "field_creative_case" => "задачником"
                              "field_dative_case" => "задачнику"
                              "field_genitive_case" => "задачника"
                              "field_nominative_case" => "задачник"
                              "field_prepositional_case" => "задачнике"
                            ]
                            "field_plural_form" => null
                            "field_short_name" => null
                            "field_short_name_foreign" => null
                            "field_translit" => "zadachnik"
                          ]
                          #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 {#1176
                      #items: array:1 [
                        0 => App\Models\Term {#1177
                          #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 [
                              "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"
                          ]
                          #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_city" => Illuminate\Database\Eloquent\Collection {#1178
                      #items: array:1 [
                        0 => App\Models\Term {#1179
                          #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 [
                              "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"
                          ]
                          #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 {#1180
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1181
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1182
                      #items: array:1 [
                        0 => App\Models\Term {#1183
                          #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" => 40
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "профильный"
                            "field_cases" => array:6 [
                              "field_accusative_case" => "профильный"
                              "field_creative_case" => "профильным"
                              "field_dative_case" => "профильному"
                              "field_genitive_case" => "профильного"
                              "field_nominative_case" => "профильный"
                              "field_prepositional_case" => "профильном"
                            ]
                            "field_translit" => "profilnyy"
                          ]
                          #original: array:6 [
                            "id" => 40
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "профильный"
                            "field_cases" => array:6 [
                              "field_accusative_case" => "профильный"
                              "field_creative_case" => "профильным"
                              "field_dative_case" => "профильному"
                              "field_genitive_case" => "профильного"
                              "field_nominative_case" => "профильный"
                              "field_prepositional_case" => "профильном"
                            ]
                            "field_translit" => "profilnyy"
                          ]
                          #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_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1184
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_publication_number" => null
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1185
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1186
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_under_the_edition_degree" => null
                    "field_cover_description" => "лупа, парень едет на велосипеде"
                    "field_publication_year" => "2008"
                    "field_publication_year_until" => null
                    "field_part" => ""
                    "field_part_writing" => ""
                    "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" => "459"
                    "field_priority" => null
                    "field_default_folder" => "/fizika_10/gelfgat-z/"
                    "field_isbn" => "978-5-89237-252-7"
                    "field_cover" => array:1 [
                      0 => "/media/fizika_10/gelfgat-z/covers/cover1.webp?ts=1756049816"
                    ]
                    "field_cover_alts" => array:1 [
                      0 => ""
                    ]
                    "field_covers" => array:1 [
                      0 => array:4 [
                        "path" => "/media/fizika_10/gelfgat-z/covers/cover1.webp?ts=1756049816"
                        "alt" => ""
                        "width" => "1566"
                        "height" => "2412"
                      ]
                    ]
                    "field_popular_book" => "0"
                    "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1187
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1188
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1189
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_url" => "/10-klass/fizika/gelfgat-zadachnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1190
                      #items: array:1 [
                        0 => App\Models\Term {#1191
                          #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" => 46
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "красный"
                            "field_cases" => array:6 [
                              "field_accusative_case" => "красный"
                              "field_creative_case" => "красным"
                              "field_dative_case" => "красному"
                              "field_genitive_case" => "красного"
                              "field_nominative_case" => "красный"
                              "field_prepositional_case" => "красном"
                            ]
                            "field_translit" => "krasnyy"
                          ]
                          #original: array:6 [
                            "id" => 46
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "красный"
                            "field_cases" => array:6 [
                              "field_accusative_case" => "красный"
                              "field_creative_case" => "красным"
                              "field_dative_case" => "красному"
                              "field_genitive_case" => "красного"
                              "field_nominative_case" => "красный"
                              "field_prepositional_case" => "красном"
                            ]
                            "field_translit" => "krasnyy"
                          ]
                          #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" => 381
                      "subject" => 556
                      "class_subject" => 494
                    ]
                  ]
                  #original: array:50 [
                    "id" => 5400
                    "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 {#1163}
                    "field_class" => Illuminate\Database\Eloquent\Collection {#1164}
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1167}
                    "field_author" => Illuminate\Database\Eloquent\Collection {#1169}
                    "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1173}
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1174}
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1176}
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1178}
                    "field_series" => Illuminate\Database\Eloquent\Collection {#1180}
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1181}
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1182}
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1184}
                    "field_publication_number" => null
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1185}
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1186}
                    "field_under_the_edition_degree" => null
                    "field_cover_description" => "лупа, парень едет на велосипеде"
                    "field_publication_year" => "2008"
                    "field_publication_year_until" => null
                    "field_part" => ""
                    "field_part_writing" => ""
                    "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" => "459"
                    "field_priority" => null
                    "field_default_folder" => "/fizika_10/gelfgat-z/"
                    "field_isbn" => "978-5-89237-252-7"
                    "field_cover" => array:1 [
                      0 => "/media/fizika_10/gelfgat-z/covers/cover1.webp?ts=1756049816"
                    ]
                    "field_cover_alts" => array:1 [
                      0 => ""
                    ]
                    "field_covers" => array:1 [
                      0 => array:4 [
                        "path" => "/media/fizika_10/gelfgat-z/covers/cover1.webp?ts=1756049816"
                        "alt" => ""
                        "width" => "1566"
                        "height" => "2412"
                      ]
                    ]
                    "field_popular_book" => "0"
                    "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1187}
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1188}
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1189}
                    "field_url" => "/10-klass/fizika/gelfgat-zadachnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1190}
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "breadcrumbs" => array:3 [
                      "class" => 381
                      "subject" => 556
                      "class_subject" => 494
                    ]
                  ]
                  #changes: []
                  #casts: []
                  #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 {#1192
              #items: []
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1319266
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Механика"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1160}
            "field_page_start" => "6"
            "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 {#1194}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1192}
          ]
          #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 {#1193
          #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" => 1319296
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Законы сохранения в механике"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1195
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "73"
            "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 {#1196
              #items: array:1 [
                0 => App\Models\Book {#1161}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1197
              #items: array:1 [
                0 => App\Models\Branch {#1034}
              ]
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1319296
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Законы сохранения в механике"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1195}
            "field_page_start" => "73"
            "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 {#1196}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1197}
          ]
          #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 {#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" => 1319297
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "10. Импульс. Закон сохранения импульса"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1199
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "73"
            "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 {#1161}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1242
              #items: array:1 [
                0 => App\Models\Branch {#1201
                  #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" => 1319296
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Законы сохранения в механике"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1203
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_page_start" => "73"
                    "field_branch_display" => "0"
                    "field_branch_expanded" => "0"
                    "field_display_branch_in_title" => "1"
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                    "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 {#1202
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1235
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                  ]
                  #original: array:24 [
                    "id" => 1319296
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Законы сохранения в механике"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1203}
                    "field_page_start" => "73"
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                    "field_display_branch_in_title" => "1"
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                    "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 {#1202}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1235}
                  ]
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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" => 1319297
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "10. Импульс. Закон сохранения импульса"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1199}
            "field_page_start" => "73"
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            "field_display_branch_in_title" => "1"
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            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1200}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1242}
          ]
          #changes: []
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          #classCastCache: []
          #attributeCastCache: []
          #dateFormat: null
          #appends: []
          #dispatchesEvents: []
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          #touches: []
          +timestamps: true
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          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
        3 => App\Models\Branch {#1240
          #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" => 1319299
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Олимпиадные задачи"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1241
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "74"
            "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 {#1243
              #items: array:1 [
                0 => App\Models\Book {#1161}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1252
              #items: array:1 [
                0 => App\Models\Branch {#1251
                  #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" => 1319297
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "10. Импульс. Закон сохранения импульса"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1253
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_page_start" => "73"
                    "field_branch_display" => "0"
                    "field_branch_expanded" => "0"
                    "field_display_branch_in_title" => "1"
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                    "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 {#1254
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1255
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                  ]
                  #original: array:24 [
                    "id" => 1319297
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "10. Импульс. Закон сохранения импульса"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1253}
                    "field_page_start" => "73"
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                    "field_display_branch_in_title" => "1"
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                    "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 {#1254}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1255}
                  ]
                  #changes: []
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                  #attributeCastCache: []
                  #dateFormat: null
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                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1319299
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Олимпиадные задачи"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1241}
            "field_page_start" => "74"
            "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 {#1243}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1252}
          ]
          #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
    }
    "content" => Illuminate\Database\Eloquent\Collection {#1108
      #items: array:2 [
        0 => App\Models\Element {#1138
          #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" => 1494018
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1128
              #items: array:1 [
                0 => App\Models\Edition {#1137
                  #connection: "mysql"
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            "text" => "<p><strong>O-40.</strong> На конце соломинки массой $\text{M}$ и небольшой длины $\text{l}$, лежащей на гладком столе, сидит кузнечик, масса которого $\text{m}$. С какой наименьшей скоростью $\text{v}$ он должен прыгнуть, чтобы попасть на другой конец соломинки? Трением между столом и соломинкой пренебречь, соломинка не должна вращаться.</p><p>☑ $v = \sqrt{\frac{M}{m+M}} gl.$</p><p><strong><em>Решение.</em></strong> Если скорость кузнечика направлена под углом 45° к горизонту, то $v_\text{г} = v_\text{в}$. Оттолкнувшись от соломинки, кузнечик сообщит ей импульс, проекция которого на горизонтальное направление $Mv_c$ равна $mv_\text{г}$. В результате соломинка переместится на расстояние $s_1 = v_c t$ в направлении, противоположном $v_c$. Кузнечик за это же время пролетит в горизонтальном направлении расстояние $s_2 = v_\text{г} t$ ($s_2 &lt; l$). Чтобы кузнечик попал на конец соломинки, необходимо выполнение следующего условия: $s_1 + s_2 = l$.</p><p>Учитывая, что полет кузнечика продолжается $t = \frac{2v_\text{в}}{g}$, а скорость соломинки $v_c = \frac{m}{M} v_\text{г}$, получим $\frac{m}{M} v_\text{г} \frac{2v_\text{в}}{g} + v_\text{г} \frac{2v_\text{в}}{g} = l$.</p><p>Поскольку $v_\text{г} = v_\text{в} = \frac{v}{\sqrt{2}}$, то $\frac{v^2}{g} \frac{m+M}{M} = l$, откуда $v = \sqrt{\frac{M}{m+M}} gl$.</p>"
            "img" => array:1 [
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          #original: array:7 [
            "id" => 1494018
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1128}
            "task" => array:2 [
              "refs" => "1319496"
              "type" => "task"
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            "text" => "<p><strong>O-40.</strong> На конце соломинки массой $\text{M}$ и небольшой длины $\text{l}$, лежащей на гладком столе, сидит кузнечик, масса которого $\text{m}$. С какой наименьшей скоростью $\text{v}$ он должен прыгнуть, чтобы попасть на другой конец соломинки? Трением между столом и соломинкой пренебречь, соломинка не должна вращаться.</p><p>☑ $v = \sqrt{\frac{M}{m+M}} gl.$</p><p><strong><em>Решение.</em></strong> Если скорость кузнечика направлена под углом 45° к горизонту, то $v_\text{г} = v_\text{в}$. Оттолкнувшись от соломинки, кузнечик сообщит ей импульс, проекция которого на горизонтальное направление $Mv_c$ равна $mv_\text{г}$. В результате соломинка переместится на расстояние $s_1 = v_c t$ в направлении, противоположном $v_c$. Кузнечик за это же время пролетит в горизонтальном направлении расстояние $s_2 = v_\text{г} t$ ($s_2 &lt; l$). Чтобы кузнечик попал на конец соломинки, необходимо выполнение следующего условия: $s_1 + s_2 = l$.</p><p>Учитывая, что полет кузнечика продолжается $t = \frac{2v_\text{в}}{g}$, а скорость соломинки $v_c = \frac{m}{M} v_\text{г}$, получим $\frac{m}{M} v_\text{г} \frac{2v_\text{в}}{g} + v_\text{г} \frac{2v_\text{в}}{g} = l$.</p><p>Поскольку $v_\text{г} = v_\text{в} = \frac{v}{\sqrt{2}}$, то $\frac{v^2}{g} \frac{m+M}{M} = l$, откуда $v = \sqrt{\frac{M}{m+M}} gl$.</p>"
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            "created_at" => "2026-04-10 13:58:26"
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            "edition" => Illuminate\Database\Eloquent\Collection {#1122
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                    "created_at" => "2026-04-10 13:58:26"
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            "task" => array:2 [
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            "text" => "<p><strong>Дано:</strong><br>Масса соломинки: $M$<br>Масса кузнечика: $m$<br>Длина соломинки: $l$<br>Ускорение свободного падения: $g$<br></p><p><strong>Найти:</strong><br>Минимальную скорость $v$, с которой должен прыгнуть кузнечик.</p><p><strong>Решение:</strong></p><p>Рассмотрим систему, состоящую из кузнечика и соломинки. Так как по условию трением между столом и соломинкой можно пренебречь, система является замкнутой в горизонтальном направлении. Следовательно, для горизонтальной оси выполняется закон сохранения импульса.</p><p>В начальный момент система покоится, поэтому ее суммарный импульс равен нулю. Пусть кузнечик прыгает со скоростью $\vec{v}$, составляющей угол $\alpha$ с горизонтом. Горизонтальная составляющая скорости кузнечика относительно стола равна $v_x = v \cos\alpha$, а вертикальная – $v_y = v \sin\alpha$.</p><p>В результате толчка соломинка начнет двигаться в противоположном направлении со скоростью $V_c$. Запишем закон сохранения импульса в проекции на горизонтальную ось:</p><p>$0 = m v_x + M V_c$</p><p>Отсюда выразим скорость соломинки:</p><p>$V_c = - \frac{m}{M} v_x$</p><p>Знак «минус» указывает на то, что соломинка движется в направлении, противоположном горизонтальному движению кузнечика.</p><p>Время полета кузнечика $t$ определяется его движением по вертикали. Кузнечик взлетает с соломинки и приземляется на нее, то есть на ту же высоту. Время полета равно:</p><p>$t = \frac{2v_y}{g}$</p><p>За время полета $t$ кузнечик пролетит по горизонтали расстояние $s_k$ относительно стола:</p><p>$s_k = v_x t$</p><p>За это же время соломинка сместится в обратном направлении на расстояние $s_c$:</p><p>$s_c = |V_c| t = \frac{m}{M} v_x t$</p><p>Чтобы кузнечик приземлился на другой конец соломинки, суммарное горизонтальное расстояние, на которое они разлетятся друг от друга, должно быть равно длине соломинки $l$.</p><p>$s_k + s_c = l$</p><p>Подставим выражения для $s_k$ и $s_c$:</p><p>$v_x t + \frac{m}{M} v_x t = l$</p><p>$v_x t (1 + \frac{m}{M}) = l \implies v_x t (\frac{M+m}{M}) = l$</p><p>Теперь подставим в это уравнение выражение для времени полета $t = \frac{2v_y}{g}$:</p><p>$v_x (\frac{2v_y}{g}) (\frac{M+m}{M}) = l$</p><p>Отсюда получаем связь между компонентами скорости:</p><p>$v_x v_y = \frac{glM}{2(m+M)}$</p><p>Нам нужно найти минимальную начальную скорость $v$. Величина скорости связана с ее компонентами соотношением $v^2 = v_x^2 + v_y^2$. Требуется минимизировать $v^2$ при условии, что произведение $v_x v_y$ является константой. Обозначим эту константу $C = \frac{glM}{2(m+M)}$.</p><p>Минимум суммы $v_x^2 + v_y^2$ при постоянном произведении $v_x v_y = C$ достигается, когда слагаемые равны, то есть $v_x^2 = v_y^2$, или $v_x = v_y$ (так как проекции скорости на оси положительны). Это соответствует углу прыжка $\alpha = 45^\circ$, поскольку $\tan\alpha = \frac{v_y}{v_x} = 1$.</p><p>При условии $v_x = v_y$ получаем:</p><p>$v_x^2 = \frac{glM}{2(m+M)}$</p><p>Тогда квадрат минимальной скорости равен:</p><p>$v^2 = v_x^2 + v_y^2 = 2v_x^2 = 2 \cdot \frac{glM}{2(m+M)} = \frac{glM}{m+M}$</p><p>Следовательно, наименьшая скорость, с которой должен прыгнуть кузнечик, равна:</p><p>$v = \sqrt{\frac{M}{m+M}gl}$</p><p><strong>Ответ:</strong> $v = \sqrt{\frac{M}{m+M}gl}$</p>"
          ]
          #original: array:6 [
            "id" => 1691575
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1122}
            "task" => array:2 [
              "refs" => "1319496"
              "type" => "task"
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            "text" => "<p><strong>Дано:</strong><br>Масса соломинки: $M$<br>Масса кузнечика: $m$<br>Длина соломинки: $l$<br>Ускорение свободного падения: $g$<br></p><p><strong>Найти:</strong><br>Минимальную скорость $v$, с которой должен прыгнуть кузнечик.</p><p><strong>Решение:</strong></p><p>Рассмотрим систему, состоящую из кузнечика и соломинки. Так как по условию трением между столом и соломинкой можно пренебречь, система является замкнутой в горизонтальном направлении. Следовательно, для горизонтальной оси выполняется закон сохранения импульса.</p><p>В начальный момент система покоится, поэтому ее суммарный импульс равен нулю. Пусть кузнечик прыгает со скоростью $\vec{v}$, составляющей угол $\alpha$ с горизонтом. Горизонтальная составляющая скорости кузнечика относительно стола равна $v_x = v \cos\alpha$, а вертикальная – $v_y = v \sin\alpha$.</p><p>В результате толчка соломинка начнет двигаться в противоположном направлении со скоростью $V_c$. Запишем закон сохранения импульса в проекции на горизонтальную ось:</p><p>$0 = m v_x + M V_c$</p><p>Отсюда выразим скорость соломинки:</p><p>$V_c = - \frac{m}{M} v_x$</p><p>Знак «минус» указывает на то, что соломинка движется в направлении, противоположном горизонтальному движению кузнечика.</p><p>Время полета кузнечика $t$ определяется его движением по вертикали. Кузнечик взлетает с соломинки и приземляется на нее, то есть на ту же высоту. Время полета равно:</p><p>$t = \frac{2v_y}{g}$</p><p>За время полета $t$ кузнечик пролетит по горизонтали расстояние $s_k$ относительно стола:</p><p>$s_k = v_x t$</p><p>За это же время соломинка сместится в обратном направлении на расстояние $s_c$:</p><p>$s_c = |V_c| t = \frac{m}{M} v_x t$</p><p>Чтобы кузнечик приземлился на другой конец соломинки, суммарное горизонтальное расстояние, на которое они разлетятся друг от друга, должно быть равно длине соломинки $l$.</p><p>$s_k + s_c = l$</p><p>Подставим выражения для $s_k$ и $s_c$:</p><p>$v_x t + \frac{m}{M} v_x t = l$</p><p>$v_x t (1 + \frac{m}{M}) = l \implies v_x t (\frac{M+m}{M}) = l$</p><p>Теперь подставим в это уравнение выражение для времени полета $t = \frac{2v_y}{g}$:</p><p>$v_x (\frac{2v_y}{g}) (\frac{M+m}{M}) = l$</p><p>Отсюда получаем связь между компонентами скорости:</p><p>$v_x v_y = \frac{glM}{2(m+M)}$</p><p>Нам нужно найти минимальную начальную скорость $v$. Величина скорости связана с ее компонентами соотношением $v^2 = v_x^2 + v_y^2$. Требуется минимизировать $v^2$ при условии, что произведение $v_x v_y$ является константой. Обозначим эту константу $C = \frac{glM}{2(m+M)}$.</p><p>Минимум суммы $v_x^2 + v_y^2$ при постоянном произведении $v_x v_y = C$ достигается, когда слагаемые равны, то есть $v_x^2 = v_y^2$, или $v_x = v_y$ (так как проекции скорости на оси положительны). Это соответствует углу прыжка $\alpha = 45^\circ$, поскольку $\tan\alpha = \frac{v_y}{v_x} = 1$.</p><p>При условии $v_x = v_y$ получаем:</p><p>$v_x^2 = \frac{glM}{2(m+M)}$</p><p>Тогда квадрат минимальной скорости равен:</p><p>$v^2 = v_x^2 + v_y^2 = 2v_x^2 = 2 \cdot \frac{glM}{2(m+M)} = \frac{glM}{m+M}$</p><p>Следовательно, наименьшая скорость, с которой должен прыгнуть кузнечик, равна:</p><p>$v = \sqrt{\frac{M}{m+M}gl}$</p><p><strong>Ответ:</strong> $v = \sqrt{\frac{M}{m+M}gl}$</p>"
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№40 (с. 75)
Условие. №40 (с. 75)
скриншот условия
Физика, 10-11 класс Задачник, авторы: Гельфгат Илья Маркович, Генденштейн Лев Элевич, Кирик Леонид Анатольевич, издательство Илекса, Москва, 2008, красного цвета, страница 75, номер 40, Условие

O-40. На конце соломинки массой $\text{M}$ и небольшой длины $\text{l}$, лежащей на гладком столе, сидит кузнечик, масса которого $\text{m}$. С какой наименьшей скоростью $\text{v}$ он должен прыгнуть, чтобы попасть на другой конец соломинки? Трением между столом и соломинкой пренебречь, соломинка не должна вращаться.

☑ $v = \sqrt{\frac{M}{m+M}} gl.$

Решение. Если скорость кузнечика направлена под углом 45° к горизонту, то $v_\text{г} = v_\text{в}$. Оттолкнувшись от соломинки, кузнечик сообщит ей импульс, проекция которого на горизонтальное направление $Mv_c$ равна $mv_\text{г}$. В результате соломинка переместится на расстояние $s_1 = v_c t$ в направлении, противоположном $v_c$. Кузнечик за это же время пролетит в горизонтальном направлении расстояние $s_2 = v_\text{г} t$ ($s_2 < l$). Чтобы кузнечик попал на конец соломинки, необходимо выполнение следующего условия: $s_1 + s_2 = l$.

Учитывая, что полет кузнечика продолжается $t = \frac{2v_\text{в}}{g}$, а скорость соломинки $v_c = \frac{m}{M} v_\text{г}$, получим $\frac{m}{M} v_\text{г} \frac{2v_\text{в}}{g} + v_\text{г} \frac{2v_\text{в}}{g} = l$.

Поскольку $v_\text{г} = v_\text{в} = \frac{v}{\sqrt{2}}$, то $\frac{v^2}{g} \frac{m+M}{M} = l$, откуда $v = \sqrt{\frac{M}{m+M}} gl$.

Решение. №40 (с. 75)

Дано:
Масса соломинки: $M$
Масса кузнечика: $m$
Длина соломинки: $l$
Ускорение свободного падения: $g$

Найти:
Минимальную скорость $v$, с которой должен прыгнуть кузнечик.

Решение:

Рассмотрим систему, состоящую из кузнечика и соломинки. Так как по условию трением между столом и соломинкой можно пренебречь, система является замкнутой в горизонтальном направлении. Следовательно, для горизонтальной оси выполняется закон сохранения импульса.

В начальный момент система покоится, поэтому ее суммарный импульс равен нулю. Пусть кузнечик прыгает со скоростью $\vec{v}$, составляющей угол $\alpha$ с горизонтом. Горизонтальная составляющая скорости кузнечика относительно стола равна $v_x = v \cos\alpha$, а вертикальная – $v_y = v \sin\alpha$.

В результате толчка соломинка начнет двигаться в противоположном направлении со скоростью $V_c$. Запишем закон сохранения импульса в проекции на горизонтальную ось:

$0 = m v_x + M V_c$

Отсюда выразим скорость соломинки:

$V_c = - \frac{m}{M} v_x$

Знак «минус» указывает на то, что соломинка движется в направлении, противоположном горизонтальному движению кузнечика.

Время полета кузнечика $t$ определяется его движением по вертикали. Кузнечик взлетает с соломинки и приземляется на нее, то есть на ту же высоту. Время полета равно:

$t = \frac{2v_y}{g}$

За время полета $t$ кузнечик пролетит по горизонтали расстояние $s_k$ относительно стола:

$s_k = v_x t$

За это же время соломинка сместится в обратном направлении на расстояние $s_c$:

$s_c = |V_c| t = \frac{m}{M} v_x t$

Чтобы кузнечик приземлился на другой конец соломинки, суммарное горизонтальное расстояние, на которое они разлетятся друг от друга, должно быть равно длине соломинки $l$.

$s_k + s_c = l$

Подставим выражения для $s_k$ и $s_c$:

$v_x t + \frac{m}{M} v_x t = l$

$v_x t (1 + \frac{m}{M}) = l \implies v_x t (\frac{M+m}{M}) = l$

Теперь подставим в это уравнение выражение для времени полета $t = \frac{2v_y}{g}$:

$v_x (\frac{2v_y}{g}) (\frac{M+m}{M}) = l$

Отсюда получаем связь между компонентами скорости:

$v_x v_y = \frac{glM}{2(m+M)}$

Нам нужно найти минимальную начальную скорость $v$. Величина скорости связана с ее компонентами соотношением $v^2 = v_x^2 + v_y^2$. Требуется минимизировать $v^2$ при условии, что произведение $v_x v_y$ является константой. Обозначим эту константу $C = \frac{glM}{2(m+M)}$.

Минимум суммы $v_x^2 + v_y^2$ при постоянном произведении $v_x v_y = C$ достигается, когда слагаемые равны, то есть $v_x^2 = v_y^2$, или $v_x = v_y$ (так как проекции скорости на оси положительны). Это соответствует углу прыжка $\alpha = 45^\circ$, поскольку $\tan\alpha = \frac{v_y}{v_x} = 1$.

При условии $v_x = v_y$ получаем:

$v_x^2 = \frac{glM}{2(m+M)}$

Тогда квадрат минимальной скорости равен:

$v^2 = v_x^2 + v_y^2 = 2v_x^2 = 2 \cdot \frac{glM}{2(m+M)} = \frac{glM}{m+M}$

Следовательно, наименьшая скорость, с которой должен прыгнуть кузнечик, равна:

$v = \sqrt{\frac{M}{m+M}gl}$

Ответ: $v = \sqrt{\frac{M}{m+M}gl}$

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