Номер 7.4, страница 51 - 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. Динамика. 7. Закон всемирного тяготения. Сила тяжести и вес тела. Упражнения - номер 7.4, страница 51.

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                            "id" => 5459
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "10"
                            "field_cases" => array:6 [
                              "field_accusative_case" => "десятый"
                              "field_creative_case" => "десятым"
                              "field_dative_case" => "десятому"
                              "field_genitive_case" => "десятого"
                              "field_nominative_case" => "десятый"
                              "field_prepositional_case" => "десятом"
                            ]
                            "field_translit" => "desjatyj"
                          ]
                          #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 {#1209
                          #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" => 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"
                          ]
                          #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 {#1210
                      #items: array:1 [
                        0 => App\Models\Term {#1211
                          #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 {#1212
                      #items: array:3 [
                        0 => App\Models\Term {#1213
                          #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 {#1214
                          #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 {#1215
                          #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 {#1216
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1217
                      #items: array:1 [
                        0 => App\Models\Term {#1218
                          #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 {#1219
                      #items: array:1 [
                        0 => App\Models\Term {#1220
                          #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 {#1221
                      #items: array:1 [
                        0 => App\Models\Term {#1222
                          #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 {#1223
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1224
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1225
                      #items: array:1 [
                        0 => App\Models\Term {#1226
                          #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 {#1227
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_publication_number" => null
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1228
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1229
                      #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 {#1230
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1231
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1232
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_url" => "/10-klass/fizika/gelfgat-zadachnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1233
                      #items: array:1 [
                        0 => App\Models\Term {#1234
                          #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 {#1206}
                    "field_class" => Illuminate\Database\Eloquent\Collection {#1207}
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1210}
                    "field_author" => Illuminate\Database\Eloquent\Collection {#1212}
                    "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1216}
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1217}
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1219}
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1221}
                    "field_series" => Illuminate\Database\Eloquent\Collection {#1223}
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1224}
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1225}
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1227}
                    "field_publication_number" => null
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1228}
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1229}
                    "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 {#1230}
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1231}
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1232}
                    "field_url" => "/10-klass/fizika/gelfgat-zadachnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1233}
                    "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 {#1235
              #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 {#1203}
            "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 {#1237}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1235}
          ]
          #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 {#1236
          #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" => 1319280
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Динамика"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1238
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "40"
            "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 {#1239
              #items: array:1 [
                0 => App\Models\Book {#1204}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1240
              #items: array:1 [
                0 => App\Models\Branch {#1034}
              ]
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1319280
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Динамика"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1238}
            "field_page_start" => "40"
            "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 {#1239}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1240}
          ]
          #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 {#1241
          #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" => 1319287
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "7. Закон всемирного тяготения. Сила тяжести и вес тела"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1242
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "50"
            "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 {#1204}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1285
              #items: array:1 [
                0 => App\Models\Branch {#1244
                  #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" => 1319280
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Динамика"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1246
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_page_start" => "40"
                    "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
                    "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 {#1245
                      #items: array:1 [
                        0 => App\Models\Book {#1247 …30}
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1278
                      #items: array:1 [
                        0 => App\Models\Branch {#1279 …30}
                      ]
                      #escapeWhenCastingToString: false
                    }
                  ]
                  #original: array:24 [
                    "id" => 1319280
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Динамика"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1246}
                    "field_page_start" => "40"
                    "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 {#1245}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1278}
                  ]
                  #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" => 1319287
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "7. Закон всемирного тяготения. Сила тяжести и вес тела"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1242}
            "field_page_start" => "50"
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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 {#1243}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1285}
          ]
          #changes: []
          #casts: []
          #classCastCache: []
          #attributeCastCache: []
          #dateFormat: null
          #appends: []
          #dispatchesEvents: []
          #observables: []
          #relations: []
          #touches: []
          +timestamps: true
          +usesUniqueIds: false
          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
        3 => App\Models\Branch {#1283
          #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" => 1319288
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Упражнения"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1284
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "50"
            "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 {#1286
              #items: array:1 [
                0 => App\Models\Book {#1204}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1332
              #items: array:1 [
                0 => App\Models\Branch {#1287
                  #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" => 1319287
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "7. Закон всемирного тяготения. Сила тяжести и вес тела"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1289
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_page_start" => "50"
                    "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 {#1288
                      #items: array:1 [
                        0 => App\Models\Book {#1290 …30}
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1321
                      #items: array:1 [
                        0 => App\Models\Branch {#1322 …30}
                      ]
                      #escapeWhenCastingToString: false
                    }
                  ]
                  #original: array:24 [
                    "id" => 1319287
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "7. Закон всемирного тяготения. Сила тяжести и вес тела"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1289}
                    "field_page_start" => "50"
                    "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 {#1288}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1321}
                  ]
                  #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" => 1319288
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Упражнения"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1284}
            "field_page_start" => "50"
            "field_branch_display" => "0"
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            "field_display_branch_in_title" => "1"
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            "text" => "<p><strong>7.4.</strong> Найдите силу F притяжения маленького шарика массой m и большого однородного шара массой M, в котором имеется сферическая полость (см. рисунок).</p><p>$F = \frac{GMm}{7} \left( \frac{8}{d^2} - \frac{1}{(d - R/2)^2} \right)$</p><p><strong>Указание.</strong> См. рисунок.</p><p><strong>Решение.</strong> Закон всемирного тяготения в виде $F = \frac{Mm}{r^2}$ можно применять для вычисления силы притяжения между материальной точкой и сферически симметричным телом (при этом $\text{r}$ – расстояние от центра тела до материальной точки). Сведем нашу задачу к этому случаю. Найдем сначала, на сколько увеличится сила притяжения, если заполнить полость, т. е. сделать шар сплошным и однородным. Поскольку объем шара пропорционален кубу его радиуса, объем полости составляет 1/8 всего объема шара. Поскольку масса M шара с полостью равна 7/8 массы сплошного шара, для заполнения полости потребуется шар массой $M/7$, центр которого расположен на расстоянии $d - R/2$ от шарика массой m. В результате заполнения полости сила притяжения увеличится на $F_1 = G \frac{Mm}{7(d-R/2)^2}$. Для сплошного шара применим закон всемирного тяготения в «обычном» виде; учитывая, что масса большого шара равна $8M/7$, получаем $F + F_1 = G \frac{8Mm}{7d^2}$. Отсюда $F = \frac{GMm}{7} \left( \frac{8}{d^2} - \frac{1}{(d-R/2)^2} \right)$.</p>"
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            "text" => "<p><strong>7.4.</strong> Найдите силу F притяжения маленького шарика массой m и большого однородного шара массой M, в котором имеется сферическая полость (см. рисунок).</p><p>$F = \frac{GMm}{7} \left( \frac{8}{d^2} - \frac{1}{(d - R/2)^2} \right)$</p><p><strong>Указание.</strong> См. рисунок.</p><p><strong>Решение.</strong> Закон всемирного тяготения в виде $F = \frac{Mm}{r^2}$ можно применять для вычисления силы притяжения между материальной точкой и сферически симметричным телом (при этом $\text{r}$ – расстояние от центра тела до материальной точки). Сведем нашу задачу к этому случаю. Найдем сначала, на сколько увеличится сила притяжения, если заполнить полость, т. е. сделать шар сплошным и однородным. Поскольку объем шара пропорционален кубу его радиуса, объем полости составляет 1/8 всего объема шара. Поскольку масса M шара с полостью равна 7/8 массы сплошного шара, для заполнения полости потребуется шар массой $M/7$, центр которого расположен на расстоянии $d - R/2$ от шарика массой m. В результате заполнения полости сила притяжения увеличится на $F_1 = G \frac{Mm}{7(d-R/2)^2}$. Для сплошного шара применим закон всемирного тяготения в «обычном» виде; учитывая, что масса большого шара равна $8M/7$, получаем $F + F_1 = G \frac{8Mm}{7d^2}$. Отсюда $F = \frac{GMm}{7} \left( \frac{8}{d^2} - \frac{1}{(d-R/2)^2} \right)$.</p>"
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            "text" => "<p><strong>Дано:</strong></p><p>Масса большого шара с полостью: $M$</p><p>Масса маленького шарика: $m$</p><p>Радиус большого шара: $R$</p><p>Радиус сферической полости: $R_{пол} = R/2$</p><p>Расстояние от центра большого шара до шарика m: $d$</p><p>Гравитационная постоянная: $G$</p><p><strong>Найти:</strong></p><p>Силу притяжения $F$</p><p><strong>Решение:</strong></p><p>Для решения задачи воспользуемся принципом суперпозиции. Силу притяжения шара с полостью можно представить как разность сил притяжения сплошного шара (без полости) и силы притяжения той части, которая была удалена для создания полости.</p><p><strong>1.</strong> Найдем массу сплошного шара ($M_{спл}$) и массу удаленной части ($M_{пол}$).</p><p>Пусть $\rho$ — плотность материала большого шара. Объем сплошного шара радиусом $R$ равен $V_{спл} = \frac{4}{3}\pi R^3$.</p><p>Объем полости, которая является шаром радиусом $R/2$, равен $V_{пол} = \frac{4}{3}\pi (R/2)^3 = \frac{4}{3}\pi \frac{R^3}{8} = \frac{1}{8}V_{спл}$.</p><p>Объем шара с полостью равен $V = V_{спл} - V_{пол} = V_{спл} - \frac{1}{8}V_{спл} = \frac{7}{8}V_{спл}$.</p><p>Масса шара с полостью дана и равна $M$. Тогда $M = \rho V = \rho \frac{7}{8}V_{спл}$.</p><p>Отсюда можно выразить массу гипотетического сплошного шара (до удаления полости):</p><p>$M_{спл} = \rho V_{спл} = \rho \left(\frac{8}{7}V\right) = \frac{8}{7}(\rho V) = \frac{8}{7}M$.</p><p>Масса удаленной части (полости) равна:</p><p>$M_{пол} = \rho V_{пол} = \rho \left(\frac{1}{8}V_{спл}\right) = \frac{1}{8}M_{спл} = \frac{1}{8}\left(\frac{8}{7}M\right) = \frac{1}{7}M$.</p><p><strong>2.</strong> Рассчитаем силы по отдельности.</p><p>Сила притяжения со стороны сплошного шара массой $M_{спл}$ на шарик $m$, находящийся на расстоянии $d$ от его центра:</p><p>$F_{спл} = G \frac{M_{спл} m}{d^2} = G \frac{(\frac{8}{7}M) m}{d^2} = \frac{8}{7} \frac{GMm}{d^2}$.</p><p>Сила притяжения со стороны "удаленного" шара массой $M_{пол}$. Центр этого шара, согласно рисунку, находится на расстоянии $R - R/2 = R/2$ от центра большого шара. Таким образом, расстояние от центра полости до шарика $m$ равно $d - R/2$.</p><p>$F_{пол} = G \frac{M_{пол} m}{(d - R/2)^2} = G \frac{(\frac{1}{7}M) m}{(d - R/2)^2} = \frac{1}{7} \frac{GMm}{(d - R/2)^2}$.</p><p><strong>3.</strong> Найдем результирующую силу.</p><p>Искомая сила $F$ равна разности сил $F_{спл}$ и $F_{пол}$ (так как мы "убираем" массу, мы должны вычесть ее гравитационное воздействие):</p><p>$F = F_{спл} - F_{пол} = \frac{8}{7} \frac{GMm}{d^2} - \frac{1}{7} \frac{GMm}{(d - R/2)^2}$.</p><p>Вынесем общий множитель за скобки:</p><p>$F = \frac{GMm}{7} \left( \frac{8}{d^2} - \frac{1}{(d - R/2)^2} \right)$.</p><p><strong>Ответ:</strong> $F = \frac{GMm}{7} \left( \frac{8}{d^2} - \frac{1}{(d - R/2)^2} \right)$.</p>"
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            "text" => "<p><strong>Дано:</strong></p><p>Масса большого шара с полостью: $M$</p><p>Масса маленького шарика: $m$</p><p>Радиус большого шара: $R$</p><p>Радиус сферической полости: $R_{пол} = R/2$</p><p>Расстояние от центра большого шара до шарика m: $d$</p><p>Гравитационная постоянная: $G$</p><p><strong>Найти:</strong></p><p>Силу притяжения $F$</p><p><strong>Решение:</strong></p><p>Для решения задачи воспользуемся принципом суперпозиции. Силу притяжения шара с полостью можно представить как разность сил притяжения сплошного шара (без полости) и силы притяжения той части, которая была удалена для создания полости.</p><p><strong>1.</strong> Найдем массу сплошного шара ($M_{спл}$) и массу удаленной части ($M_{пол}$).</p><p>Пусть $\rho$ — плотность материала большого шара. Объем сплошного шара радиусом $R$ равен $V_{спл} = \frac{4}{3}\pi R^3$.</p><p>Объем полости, которая является шаром радиусом $R/2$, равен $V_{пол} = \frac{4}{3}\pi (R/2)^3 = \frac{4}{3}\pi \frac{R^3}{8} = \frac{1}{8}V_{спл}$.</p><p>Объем шара с полостью равен $V = V_{спл} - V_{пол} = V_{спл} - \frac{1}{8}V_{спл} = \frac{7}{8}V_{спл}$.</p><p>Масса шара с полостью дана и равна $M$. Тогда $M = \rho V = \rho \frac{7}{8}V_{спл}$.</p><p>Отсюда можно выразить массу гипотетического сплошного шара (до удаления полости):</p><p>$M_{спл} = \rho V_{спл} = \rho \left(\frac{8}{7}V\right) = \frac{8}{7}(\rho V) = \frac{8}{7}M$.</p><p>Масса удаленной части (полости) равна:</p><p>$M_{пол} = \rho V_{пол} = \rho \left(\frac{1}{8}V_{спл}\right) = \frac{1}{8}M_{спл} = \frac{1}{8}\left(\frac{8}{7}M\right) = \frac{1}{7}M$.</p><p><strong>2.</strong> Рассчитаем силы по отдельности.</p><p>Сила притяжения со стороны сплошного шара массой $M_{спл}$ на шарик $m$, находящийся на расстоянии $d$ от его центра:</p><p>$F_{спл} = G \frac{M_{спл} m}{d^2} = G \frac{(\frac{8}{7}M) m}{d^2} = \frac{8}{7} \frac{GMm}{d^2}$.</p><p>Сила притяжения со стороны "удаленного" шара массой $M_{пол}$. Центр этого шара, согласно рисунку, находится на расстоянии $R - R/2 = R/2$ от центра большого шара. Таким образом, расстояние от центра полости до шарика $m$ равно $d - R/2$.</p><p>$F_{пол} = G \frac{M_{пол} m}{(d - R/2)^2} = G \frac{(\frac{1}{7}M) m}{(d - R/2)^2} = \frac{1}{7} \frac{GMm}{(d - R/2)^2}$.</p><p><strong>3.</strong> Найдем результирующую силу.</p><p>Искомая сила $F$ равна разности сил $F_{спл}$ и $F_{пол}$ (так как мы "убираем" массу, мы должны вычесть ее гравитационное воздействие):</p><p>$F = F_{спл} - F_{пол} = \frac{8}{7} \frac{GMm}{d^2} - \frac{1}{7} \frac{GMm}{(d - R/2)^2}$.</p><p>Вынесем общий множитель за скобки:</p><p>$F = \frac{GMm}{7} \left( \frac{8}{d^2} - \frac{1}{(d - R/2)^2} \right)$.</p><p><strong>Ответ:</strong> $F = \frac{GMm}{7} \left( \frac{8}{d^2} - \frac{1}{(d - R/2)^2} \right)$.</p>"
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№7.4 (с. 51)
Условие. №7.4 (с. 51)
скриншот условия
Физика, 10-11 класс Задачник, авторы: Гельфгат Илья Маркович, Генденштейн Лев Элевич, Кирик Леонид Анатольевич, издательство Илекса, Москва, 2008, красного цвета, страница 51, номер 7.4, Условие
Физика, 10-11 класс Задачник, авторы: Гельфгат Илья Маркович, Генденштейн Лев Элевич, Кирик Леонид Анатольевич, издательство Илекса, Москва, 2008, красного цвета, страница 51, номер 7.4, Условие (продолжение 2)

7.4. Найдите силу F притяжения маленького шарика массой m и большого однородного шара массой M, в котором имеется сферическая полость (см. рисунок).

$F = \frac{GMm}{7} \left( \frac{8}{d^2} - \frac{1}{(d - R/2)^2} \right)$

Указание. См. рисунок.

Решение. Закон всемирного тяготения в виде $F = \frac{Mm}{r^2}$ можно применять для вычисления силы притяжения между материальной точкой и сферически симметричным телом (при этом $\text{r}$ – расстояние от центра тела до материальной точки). Сведем нашу задачу к этому случаю. Найдем сначала, на сколько увеличится сила притяжения, если заполнить полость, т. е. сделать шар сплошным и однородным. Поскольку объем шара пропорционален кубу его радиуса, объем полости составляет 1/8 всего объема шара. Поскольку масса M шара с полостью равна 7/8 массы сплошного шара, для заполнения полости потребуется шар массой $M/7$, центр которого расположен на расстоянии $d - R/2$ от шарика массой m. В результате заполнения полости сила притяжения увеличится на $F_1 = G \frac{Mm}{7(d-R/2)^2}$. Для сплошного шара применим закон всемирного тяготения в «обычном» виде; учитывая, что масса большого шара равна $8M/7$, получаем $F + F_1 = G \frac{8Mm}{7d^2}$. Отсюда $F = \frac{GMm}{7} \left( \frac{8}{d^2} - \frac{1}{(d-R/2)^2} \right)$.

Решение. №7.4 (с. 51)

Дано:

Масса большого шара с полостью: $M$

Масса маленького шарика: $m$

Радиус большого шара: $R$

Радиус сферической полости: $R_{пол} = R/2$

Расстояние от центра большого шара до шарика m: $d$

Гравитационная постоянная: $G$

Найти:

Силу притяжения $F$

Решение:

Для решения задачи воспользуемся принципом суперпозиции. Силу притяжения шара с полостью можно представить как разность сил притяжения сплошного шара (без полости) и силы притяжения той части, которая была удалена для создания полости.

1. Найдем массу сплошного шара ($M_{спл}$) и массу удаленной части ($M_{пол}$).

Пусть $\rho$ — плотность материала большого шара. Объем сплошного шара радиусом $R$ равен $V_{спл} = \frac{4}{3}\pi R^3$.

Объем полости, которая является шаром радиусом $R/2$, равен $V_{пол} = \frac{4}{3}\pi (R/2)^3 = \frac{4}{3}\pi \frac{R^3}{8} = \frac{1}{8}V_{спл}$.

Объем шара с полостью равен $V = V_{спл} - V_{пол} = V_{спл} - \frac{1}{8}V_{спл} = \frac{7}{8}V_{спл}$.

Масса шара с полостью дана и равна $M$. Тогда $M = \rho V = \rho \frac{7}{8}V_{спл}$.

Отсюда можно выразить массу гипотетического сплошного шара (до удаления полости):

$M_{спл} = \rho V_{спл} = \rho \left(\frac{8}{7}V\right) = \frac{8}{7}(\rho V) = \frac{8}{7}M$.

Масса удаленной части (полости) равна:

$M_{пол} = \rho V_{пол} = \rho \left(\frac{1}{8}V_{спл}\right) = \frac{1}{8}M_{спл} = \frac{1}{8}\left(\frac{8}{7}M\right) = \frac{1}{7}M$.

2. Рассчитаем силы по отдельности.

Сила притяжения со стороны сплошного шара массой $M_{спл}$ на шарик $m$, находящийся на расстоянии $d$ от его центра:

$F_{спл} = G \frac{M_{спл} m}{d^2} = G \frac{(\frac{8}{7}M) m}{d^2} = \frac{8}{7} \frac{GMm}{d^2}$.

Сила притяжения со стороны "удаленного" шара массой $M_{пол}$. Центр этого шара, согласно рисунку, находится на расстоянии $R - R/2 = R/2$ от центра большого шара. Таким образом, расстояние от центра полости до шарика $m$ равно $d - R/2$.

$F_{пол} = G \frac{M_{пол} m}{(d - R/2)^2} = G \frac{(\frac{1}{7}M) m}{(d - R/2)^2} = \frac{1}{7} \frac{GMm}{(d - R/2)^2}$.

3. Найдем результирующую силу.

Искомая сила $F$ равна разности сил $F_{спл}$ и $F_{пол}$ (так как мы "убираем" массу, мы должны вычесть ее гравитационное воздействие):

$F = F_{спл} - F_{пол} = \frac{8}{7} \frac{GMm}{d^2} - \frac{1}{7} \frac{GMm}{(d - R/2)^2}$.

Вынесем общий множитель за скобки:

$F = \frac{GMm}{7} \left( \frac{8}{d^2} - \frac{1}{(d - R/2)^2} \right)$.

Ответ: $F = \frac{GMm}{7} \left( \frac{8}{d^2} - \frac{1}{(d - R/2)^2} \right)$.

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