Номер 17, страница 140, часть 1 - гдз по физике 9 класс учебник Генденштейн, Булатова

Авторы: Генденштейн Л. Э., Булатова А. А., Корнильев И. Н., Кошкина А. В.

Тип: Учебник

Издательство: Бином

Год издания: 2016 - 2026

Часть: 1

Цвет обложки: бирюзовый

ISBN: 978-5-9963-3062-1

Часть 1. Механические явления. Глава III. Законы сохранения в механике. Параграф 16. Механическая работа. Мощность - номер 17, страница 140.

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                        0 => App\Models\Term {#1247
                          #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" => 5208
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Бином"
                            "field_cases" => null
                            "field_translit" => "binom"
                          ]
                          #original: array:6 [
                            "id" => 5208
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Бином"
                            "field_cases" => null
                            "field_translit" => "binom"
                          ]
                          #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 {#1248
                      #items: array:4 [
                        0 => App\Models\Term {#1249
                          #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 => "*"
                          ]
                        }
                        1 => App\Models\Term {#1250
                          #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" => 3936
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Булатова"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Альбина"
                            "field_patronymic" => "Александрова"
                            "field_surname_rp" => null
                          ]
                          #original: array:12 [
                            "id" => 3936
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Булатова"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Альбина"
                            "field_patronymic" => "Александрова"
                            "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 => "*"
                          ]
                        }
                        2 => App\Models\Term {#1251
                          #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" => 4679
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Корнильев"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Игорь"
                            "field_patronymic" => "Николаевич"
                            "field_surname_rp" => null
                          ]
                          #original: array:12 [
                            "id" => 4679
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Корнильев"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Игорь"
                            "field_patronymic" => "Николаевич"
                            "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 => "*"
                          ]
                        }
                        3 => App\Models\Term {#1252
                          #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" => 4758
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Кошкина"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Анжелика"
                            "field_patronymic" => "Васильевна"
                            "field_surname_rp" => null
                          ]
                          #original: array:12 [
                            "id" => 4758
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Кошкина"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Анжелика"
                            "field_patronymic" => "Васильевна"
                            "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 {#1253
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1254
                      #items: array:1 [
                        0 => App\Models\Term {#1255
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:10 [
                            "id" => 6671
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Учебник"
                            "field_book_type_foreign" => null
                            "field_cases" => array:6 [ …6]
                            "field_plural_form" => null
                            "field_short_name" => null
                            "field_short_name_foreign" => null
                            "field_translit" => "uchebnik"
                          ]
                          #original: array:10 [
                            "id" => 6671
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Учебник"
                            "field_book_type_foreign" => null
                            "field_cases" => array:6 [ …6]
                            "field_plural_form" => null
                            "field_short_name" => null
                            "field_short_name_foreign" => null
                            "field_translit" => "uchebnik"
                          ]
                          #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 {#1256
                      #items: array:1 [
                        0 => App\Models\Term {#1257
                          #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 [ …6]
                            "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 [ …6]
                            "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 {#1258
                      #items: array:1 [
                        0 => App\Models\Term {#1259
                          #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 [ …6]
                            "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 [ …6]
                            "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 {#1260
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1261
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1262
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1263
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_publication_number" => null
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1264
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1265
                      #items: array:1 [
                        0 => App\Models\Term {#1266
                          #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" => 5395
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Орлов"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Владимир"
                            "field_patronymic" => "Алексеевич"
                            "field_surname_rp" => "Орлова"
                          ]
                          #original: array:12 [
                            "id" => 5395
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Орлов"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Владимир"
                            "field_patronymic" => "Алексеевич"
                            "field_surname_rp" => "Орлова"
                          ]
                          #changes: []
                          #casts: []
                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
                          +usesUniqueIds: false
                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_under_the_edition_degree" => null
                    "field_cover_description" => null
                    "field_publication_year" => "2016"
                    "field_publication_year_until" => null
                    "field_part" => "1, 2"
                    "field_part_writing" => "Часть"
                    "field_second_foreign_language" => null
                    "field_for_whom" => "Учебное издание"
                    "field_allowed" => null
                    "field_reserve_field" => null
                    "field_link_to_source" => null
                    "field_tasks_count" => "1111"
                    "field_priority" => null
                    "field_default_folder" => "/fizika_09/gendenshtejn-u/"
                    "field_isbn" => "978-5-9963-3062-1"
                    "field_cover" => array:2 [
                      0 => "/media/fizika_09/gendenshtejn-u/covers/cover1.webp?ts=1759256052"
                      1 => "/media/fizika_09/gendenshtejn-u/covers/cover2.webp?ts=1759256052"
                    ]
                    "field_cover_alts" => array:2 [
                      0 => ""
                      1 => ""
                    ]
                    "field_covers" => array:2 [
                      0 => array:4 [
                        "path" => "/media/fizika_09/gendenshtejn-u/covers/cover1.webp?ts=1759256052"
                        "alt" => ""
                        "width" => "1863"
                        "height" => "2813"
                      ]
                      1 => array:4 [
                        "path" => "/media/fizika_09/gendenshtejn-u/covers/cover2.webp?ts=1759256052"
                        "alt" => ""
                        "width" => "1863"
                        "height" => "2809"
                      ]
                    ]
                    "field_popular_book" => "0"
                    "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1267
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1268
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1269
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_url" => "/9-klass/fizika/gendenshtejn-uchebnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1270
                      #items: array:1 [
                        0 => App\Models\Term {#1271
                          #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" => 6978
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "бирюзовый"
                            "field_cases" => array:6 [ …6]
                            "field_translit" => "biruzovyy"
                          ]
                          #original: array:6 [
                            "id" => 6978
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "бирюзовый"
                            "field_cases" => array:6 [ …6]
                            "field_translit" => "biruzovyy"
                          ]
                          #changes: []
                          #casts: []
                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
                          +usesUniqueIds: false
                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "breadcrumbs" => array:3 [
                      "class" => 380
                      "subject" => 556
                      "class_subject" => 493
                    ]
                  ]
                  #original: array:50 [
                    "id" => 2980
                    "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 {#1243}
                    "field_class" => Illuminate\Database\Eloquent\Collection {#1244}
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1246}
                    "field_author" => Illuminate\Database\Eloquent\Collection {#1248}
                    "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1253}
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1254}
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1256}
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1258}
                    "field_series" => Illuminate\Database\Eloquent\Collection {#1260}
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1261}
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1262}
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1263}
                    "field_publication_number" => null
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1264}
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1265}
                    "field_under_the_edition_degree" => null
                    "field_cover_description" => null
                    "field_publication_year" => "2016"
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                    "field_part" => "1, 2"
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                    "field_for_whom" => "Учебное издание"
                    "field_allowed" => null
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                    "field_link_to_source" => null
                    "field_tasks_count" => "1111"
                    "field_priority" => null
                    "field_default_folder" => "/fizika_09/gendenshtejn-u/"
                    "field_isbn" => "978-5-9963-3062-1"
                    "field_cover" => array:2 [
                      0 => "/media/fizika_09/gendenshtejn-u/covers/cover1.webp?ts=1759256052"
                      1 => "/media/fizika_09/gendenshtejn-u/covers/cover2.webp?ts=1759256052"
                    ]
                    "field_cover_alts" => array:2 [
                      0 => ""
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                    ]
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                      0 => array:4 [
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                        "width" => "1863"
                        "height" => "2813"
                      ]
                      1 => array:4 [
                        "path" => "/media/fizika_09/gendenshtejn-u/covers/cover2.webp?ts=1759256052"
                        "alt" => ""
                        "width" => "1863"
                        "height" => "2809"
                      ]
                    ]
                    "field_popular_book" => "0"
                    "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1267}
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1268}
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1269}
                    "field_url" => "/9-klass/fizika/gendenshtejn-uchebnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1270}
                    "field_metatags_title" => null
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                    "field_h1" => null
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                    "breadcrumbs" => array:3 [
                      "class" => 380
                      "subject" => 556
                      "class_subject" => 493
                    ]
                  ]
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                  #attributeCastCache: []
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                  #dispatchesEvents: []
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                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1272
              #items: []
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1433206
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => null
            "field_branch_order" => "1"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1242}
            "field_page_start" => "6"
            "field_branch_display" => "0"
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            "field_display_branch_in_title" => "1"
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            "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
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            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1274}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1272}
          ]
          #changes: []
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          #attributeCastCache: []
          #dateFormat: null
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          #hidden: []
          #visible: []
          #fillable: []
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            0 => "*"
          ]
        }
        1 => App\Models\Branch {#1273
          #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" => 1433207
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Механические явления"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1275
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "6"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
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            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
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            "field_metatags_description" => null
            "field_h1" => null
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            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1276
              #items: array:1 [
                0 => App\Models\Book {#1241}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1277
              #items: array:1 [
                0 => App\Models\Branch {#1034}
              ]
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1433207
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Механические явления"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1275}
            "field_page_start" => "6"
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            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1276}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1277}
          ]
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          #dateFormat: null
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          +timestamps: true
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          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
        2 => App\Models\Branch {#1278
          #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" => 1433223
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Законы сохранения в механике"
            "field_branch_order" => "III"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1282
              #items: array:1 [
                0 => App\Models\Term {#1279
                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:7 [
                    "id" => 29
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Глава"
                    "field_cases" => array:6 [ …6]
                    "field_page_check_not_needed" => null
                    "field_short_name" => null
                  ]
                  #original: array:7 [
                    "id" => 29
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Глава"
                    "field_cases" => array:6 [ …6]
                    "field_page_check_not_needed" => null
                    "field_short_name" => null
                  ]
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                  #attributeCastCache: []
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                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "118"
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            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1281
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                0 => App\Models\Book {#1241}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1324
              #items: array:1 [
                0 => App\Models\Branch {#1280
                  #connection: "mysql"
                  #table: "branches"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
                  #with: []
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                  #attributes: array:24 [
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                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1284 …2}
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                    "field_branch_covers" => []
                    "book" => Illuminate\Database\Eloquent\Collection {#1283 …2}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1316 …2}
                  ]
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                    "updated_at" => null
                    "field_display_title" => "Механические явления"
                    "field_branch_order" => null
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                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1284 …2}
                    "field_page_start" => "6"
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                    "field_navigation_title" => null
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                    "field_h1" => null
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                    "field_branch_cover" => []
                    "field_branch_covers" => []
                    "book" => Illuminate\Database\Eloquent\Collection {#1283 …2}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1316 …2}
                  ]
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                    0 => "*"
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              ]
              #escapeWhenCastingToString: false
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            "updated_at" => null
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            "field_branch_order" => "III"
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            "book" => Illuminate\Database\Eloquent\Collection {#1281}
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            0 => "*"
          ]
        }
        3 => App\Models\Branch {#1322
          #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" => 1433226
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Механическая работа. Мощность"
            "field_branch_order" => "16"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1327
              #items: array:1 [
                0 => App\Models\Term {#1323
                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:7 [
                    "id" => 32
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Параграф"
                    "field_cases" => array:6 [ …6]
                    "field_page_check_not_needed" => null
                    "field_short_name" => "§"
                  ]
                  #original: array:7 [
                    "id" => 32
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Параграф"
                    "field_cases" => array:6 [ …6]
                    "field_page_check_not_needed" => null
                    "field_short_name" => "§"
                  ]
                  #changes: []
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                  #attributeCastCache: []
                  #dateFormat: null
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                  +timestamps: true
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                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
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            "field_page_start" => "133"
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            "field_h1" => null
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            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1326
              #items: array:1 [
                0 => App\Models\Book {#1241}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1405
              #items: array:1 [
                0 => App\Models\Branch {#1325
                  #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" => 1433223
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Законы сохранения в механике"
                    "field_branch_order" => "III"
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1329 …2}
                    "field_page_start" => "118"
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                    "book" => Illuminate\Database\Eloquent\Collection {#1330 …2}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1362 …2}
                  ]
                  #original: array:24 [
                    "id" => 1433223
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Законы сохранения в механике"
                    "field_branch_order" => "III"
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1329 …2}
                    "field_page_start" => "118"
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                    "book" => Illuminate\Database\Eloquent\Collection {#1330 …2}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1362 …2}
                  ]
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                  +timestamps: true
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                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
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          #original: array:24 [
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            "field_display_title" => "Механическая работа. Мощность"
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            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1327}
            "field_page_start" => "133"
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            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1326}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1405}
          ]
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          +timestamps: true
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          #hidden: []
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          #guarded: array:1 [
            0 => "*"
          ]
        }
      ]
      #escapeWhenCastingToString: false
    }
    "content" => Illuminate\Database\Eloquent\Collection {#1150
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          #connection: "mysql"
          #table: "elements"
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          #keyType: "int"
          +incrementing: true
          #with: []
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          +exists: true
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          #attributes: array:7 [
            "id" => 1696485
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1214
              #items: array:1 [
                0 => App\Models\Edition {#1222
                  #connection: "mysql"
                  #table: "editions"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
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                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:21 [
                    "id" => 6168
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "title" => "Условие"
                    "field_order" => "1"
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1220 …2}
                    "field_content_type" => "free"
                    "field_content_mode" => "text, image"
                    "field_page_content_mode" => "image"
                    "field_content_text_checked" => "0"
                    "field_page_content_text_checked" => "0"
                    "field_solution_author" => "Автор"
                    "field_moderator" => "stas"
                    "field_edition_type" => "statement"
                    "field_root_dir" => "0-"
                    "field_responsible" => Illuminate\Database\Eloquent\Collection {#1218 …2}
                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1219 …2}
                    "field_process_formula" => "katex"
                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1217 …2}
                    "field_content_source" => null
                  ]
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                    "id" => 6168
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "title" => "Условие"
                    "field_order" => "1"
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1220 …2}
                    "field_content_type" => "free"
                    "field_content_mode" => "text, image"
                    "field_page_content_mode" => "image"
                    "field_content_text_checked" => "0"
                    "field_page_content_text_checked" => "0"
                    "field_solution_author" => "Автор"
                    "field_moderator" => "stas"
                    "field_edition_type" => "statement"
                    "field_root_dir" => "0-"
                    "field_responsible" => Illuminate\Database\Eloquent\Collection {#1218 …2}
                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1219 …2}
                    "field_process_formula" => "katex"
                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1217 …2}
                    "field_content_source" => null
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
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                  #touches: []
                  +timestamps: true
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                  #hidden: []
                  #visible: []
                  #fillable: []
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                    0 => "*"
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              ]
              #escapeWhenCastingToString: false
            }
            "task" => array:2 [
              "refs" => "1433744"
              "type" => "task"
            ]
            "text" => "<p><strong>17.</strong> Каков знак работы силы трения скольжения при скатывании санок с горы? Сделайте пояснительный рисунок.</p>"
            "img" => array:1 [
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                "name" => "17-1.jpg"
                "alt" => null
                "width" => "1589"
                "height" => 210
                "path" => "/media/fizika_09/gendenshtejn-u/0-16/17-1.webp?ts=1759348273"
              ]
            ]
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            "id" => 1696485
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1214}
            "task" => array:2 [
              "refs" => "1433744"
              "type" => "task"
            ]
            "text" => "<p><strong>17.</strong> Каков знак работы силы трения скольжения при скатывании санок с горы? Сделайте пояснительный рисунок.</p>"
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                "width" => "1589"
                "height" => 210
                "path" => "/media/fizika_09/gendenshtejn-u/0-16/17-1.webp?ts=1759348273"
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            0 => "*"
          ]
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          #connection: "mysql"
          #table: "elements"
          #primaryKey: "id"
          #keyType: "int"
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          +exists: true
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          #attributes: array:6 [
            "id" => 1780555
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1206
              #items: array:1 [
                0 => App\Models\Edition {#1215
                  #connection: "mysql"
                  #table: "editions"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:21 [
                    "id" => 6515
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "title" => "Решение"
                    "field_order" => "2"
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1211 …2}
                    "field_content_type" => "free"
                    "field_content_mode" => "text"
                    "field_page_content_mode" => ""
                    "field_content_text_checked" => "0"
                    "field_page_content_text_checked" => "0"
                    "field_solution_author" => "Gemini 2.5 Pro"
                    "field_moderator" => "tolik"
                    "field_edition_type" => "solution"
                    "field_root_dir" => "1-"
                    "field_responsible" => Illuminate\Database\Eloquent\Collection {#1212 …2}
                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1209 …2}
                    "field_process_formula" => "katex"
                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1210 …2}
                    "field_content_source" => null
                  ]
                  #original: array:21 [
                    "id" => 6515
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "title" => "Решение"
                    "field_order" => "2"
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1211 …2}
                    "field_content_type" => "free"
                    "field_content_mode" => "text"
                    "field_page_content_mode" => ""
                    "field_content_text_checked" => "0"
                    "field_page_content_text_checked" => "0"
                    "field_solution_author" => "Gemini 2.5 Pro"
                    "field_moderator" => "tolik"
                    "field_edition_type" => "solution"
                    "field_root_dir" => "1-"
                    "field_responsible" => Illuminate\Database\Eloquent\Collection {#1212 …2}
                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1209 …2}
                    "field_process_formula" => "katex"
                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1210 …2}
                    "field_content_source" => null
                  ]
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                  #attributeCastCache: []
                  #dateFormat: null
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                  +timestamps: true
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                    0 => "*"
                  ]
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              ]
              #escapeWhenCastingToString: false
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            "task" => array:2 [
              "refs" => "1433744"
              "type" => "task"
            ]
            "text" => "<p>Работа силы $\text{A}$ определяется как произведение модуля силы $\text{F}$, модуля перемещения $\text{s}$ и косинуса угла $\alpha$ между направлением силы и направлением перемещения. Математически это выражается формулой:$A = F \cdot s \cdot \cos(\alpha)$</p><p>Знак работы зависит от угла $\alpha$:</p><ul><li>Если угол $\alpha$ острый ($0^\circ \le \alpha &lt; 90^\circ$), то $\cos(\alpha) &gt; 0$ и работа $A &gt; 0$ (положительная).</li><li>Если угол $\alpha$ тупой ($90^\circ &lt; \alpha \le 180^\circ$), то $\cos(\alpha) &lt; 0$ и работа $A &lt; 0$ (отрицательная).</li><li>Если угол $\alpha$ прямой ($\alpha = 90^\circ$), то $\cos(\alpha) = 0$ и работа $A = 0$.</li></ul><p>В случае скатывания санок с горы, вектор перемещения $\vec{s}$ направлен вниз по склону. Сила трения скольжения $\vec{F}_{тр}$ всегда направлена в сторону, противоположную направлению движения. Следовательно, вектор силы трения $\vec{F}_{тр}$ направлен вверх по склону.</p><p>Таким образом, угол $\alpha$ между вектором силы трения $\vec{F}_{тр}$ и вектором перемещения $\vec{s}$ составляет $180^\circ$. Так как $\cos(180^\circ) = -1$, работа силы трения скольжения будет отрицательной.$A_{тр} = F_{тр} \cdot s \cdot \cos(180^\circ) = - F_{тр} \cdot s$Отрицательный знак работы означает, что действие силы трения направлено против движения, что приводит к уменьшению механической энергии санок (она переходит в тепловую энергию).</p><p>Пояснительный рисунок:</p><svg width="350" height="220" xmlns="http://www.w3.org/2000/svg" font-family="sans-serif" font-size="16"><defs><marker id="arrow-red" viewBox="0 0 10 10" refX="8" refY="5" markerWidth="5" markerHeight="5" orient="auto-start-reverse"><path d="M 0 0 L 10 5 L 0 10 z" fill="red" /></marker><marker id="arrow-blue" viewBox="0 0 10 10" refX="8" refY="5" markerWidth="5" markerHeight="5" orient="auto-start-reverse"><path d="M 0 0 L 10 5 L 0 10 z" fill="blue" /></marker><marker id="arrow-green" viewBox="0 0 10 10" refX="8" refY="5" markerWidth="5" markerHeight="5" orient="auto-start-reverse"><path d="M 0 0 L 10 5 L 0 10 z" fill="green" /></marker><marker id="arrow-purple" viewBox="0 0 10 10" refX="8" refY="5" markerWidth="5" markerHeight="5" orient="auto-start-reverse"><path d="M 0 0 L 10 5 L 0 10 z" fill="purple" /></marker></defs><!-- Slope --><path d="M 20 200 L 330 200 L 20 50 Z" fill="#e0e0e0" stroke="black" /><!-- Sled --><g transform="rotate(-25.4, 175, 125)"><rect x="155" y="115" width="40" height="20" fill="#a0522d" stroke="black" /></g><!-- Center point --><circle cx="175" cy="125" r="2" fill="black" /><!-- Vectors --><!-- Displacement s (blue) --><line x1="175" y1="125" x2="256" y2="162" stroke="blue" stroke-width="2" marker-end="url(#arrow-blue)" /><text x="260" y="168" fill="blue" font-style="italic">s</text><!-- Friction F_tr (red) --><line x1="175" y1="125" x2="122" y2="101" stroke="red" stroke-width="2" marker-end="url(#arrow-red)" /><text x="100" y="100" fill="red">F<tspan baseline-shift="sub" font-size="0.8em">тр</tspan></text><!-- Normal N (green) --><line x1="175" y1="125" x2="198" y2="78" stroke="green" stroke-width="2" marker-end="url(#arrow-green)" /><text x="202" y="75" fill="green">N</text><!-- Gravity mg (purple) --><line x1="175" y1="125" x2="175" y2="185" stroke="purple" stroke-width="2" marker-end="url(#arrow-purple)" /><text x="180" y="190" fill="purple">mg</text></svg><p><strong>Ответ:</strong> Знак работы силы трения скольжения при скатывании санок с горы — отрицательный.</p>"
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          #original: array:6 [
            "id" => 1780555
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1206}
            "task" => array:2 [
              "refs" => "1433744"
              "type" => "task"
            ]
            "text" => "<p>Работа силы $\text{A}$ определяется как произведение модуля силы $\text{F}$, модуля перемещения $\text{s}$ и косинуса угла $\alpha$ между направлением силы и направлением перемещения. Математически это выражается формулой:$A = F \cdot s \cdot \cos(\alpha)$</p><p>Знак работы зависит от угла $\alpha$:</p><ul><li>Если угол $\alpha$ острый ($0^\circ \le \alpha &lt; 90^\circ$), то $\cos(\alpha) &gt; 0$ и работа $A &gt; 0$ (положительная).</li><li>Если угол $\alpha$ тупой ($90^\circ &lt; \alpha \le 180^\circ$), то $\cos(\alpha) &lt; 0$ и работа $A &lt; 0$ (отрицательная).</li><li>Если угол $\alpha$ прямой ($\alpha = 90^\circ$), то $\cos(\alpha) = 0$ и работа $A = 0$.</li></ul><p>В случае скатывания санок с горы, вектор перемещения $\vec{s}$ направлен вниз по склону. Сила трения скольжения $\vec{F}_{тр}$ всегда направлена в сторону, противоположную направлению движения. Следовательно, вектор силы трения $\vec{F}_{тр}$ направлен вверх по склону.</p><p>Таким образом, угол $\alpha$ между вектором силы трения $\vec{F}_{тр}$ и вектором перемещения $\vec{s}$ составляет $180^\circ$. Так как $\cos(180^\circ) = -1$, работа силы трения скольжения будет отрицательной.$A_{тр} = F_{тр} \cdot s \cdot \cos(180^\circ) = - F_{тр} \cdot s$Отрицательный знак работы означает, что действие силы трения направлено против движения, что приводит к уменьшению механической энергии санок (она переходит в тепловую энергию).</p><p>Пояснительный рисунок:</p><svg width="350" height="220" xmlns="http://www.w3.org/2000/svg" font-family="sans-serif" font-size="16"><defs><marker id="arrow-red" viewBox="0 0 10 10" refX="8" refY="5" markerWidth="5" markerHeight="5" orient="auto-start-reverse"><path d="M 0 0 L 10 5 L 0 10 z" fill="red" /></marker><marker id="arrow-blue" viewBox="0 0 10 10" refX="8" refY="5" markerWidth="5" markerHeight="5" orient="auto-start-reverse"><path d="M 0 0 L 10 5 L 0 10 z" fill="blue" /></marker><marker id="arrow-green" viewBox="0 0 10 10" refX="8" refY="5" markerWidth="5" markerHeight="5" orient="auto-start-reverse"><path d="M 0 0 L 10 5 L 0 10 z" fill="green" /></marker><marker id="arrow-purple" viewBox="0 0 10 10" refX="8" refY="5" markerWidth="5" markerHeight="5" orient="auto-start-reverse"><path d="M 0 0 L 10 5 L 0 10 z" fill="purple" /></marker></defs><!-- Slope --><path d="M 20 200 L 330 200 L 20 50 Z" fill="#e0e0e0" stroke="black" /><!-- Sled --><g transform="rotate(-25.4, 175, 125)"><rect x="155" y="115" width="40" height="20" fill="#a0522d" stroke="black" /></g><!-- Center point --><circle cx="175" cy="125" r="2" fill="black" /><!-- Vectors --><!-- Displacement s (blue) --><line x1="175" y1="125" x2="256" y2="162" stroke="blue" stroke-width="2" marker-end="url(#arrow-blue)" /><text x="260" y="168" fill="blue" font-style="italic">s</text><!-- Friction F_tr (red) --><line x1="175" y1="125" x2="122" y2="101" stroke="red" stroke-width="2" marker-end="url(#arrow-red)" /><text x="100" y="100" fill="red">F<tspan baseline-shift="sub" font-size="0.8em">тр</tspan></text><!-- Normal N (green) --><line x1="175" y1="125" x2="198" y2="78" stroke="green" stroke-width="2" marker-end="url(#arrow-green)" /><text x="202" y="75" fill="green">N</text><!-- Gravity mg (purple) --><line x1="175" y1="125" x2="175" y2="185" stroke="purple" stroke-width="2" marker-end="url(#arrow-purple)" /><text x="180" y="190" fill="purple">mg</text></svg><p><strong>Ответ:</strong> Знак работы силы трения скольжения при скатывании санок с горы — отрицательный.</p>"
          ]
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          +timestamps: true
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      #escapeWhenCastingToString: false
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    "next" => array:2 [
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      "type" => "task"
    ]
    "previous" => array:2 [
      "refs" => "1433743"
      "type" => "task"
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    "book" => Illuminate\Database\Eloquent\Collection {#1193
      #items: array:1 [
        0 => App\Models\Book {#1241}
      ]
      #escapeWhenCastingToString: false
    }
    "page" => Illuminate\Database\Eloquent\Collection {#1189
      #items: array:1 [
        0 => App\Models\BookPage {#1225
          #connection: "mysql"
          #table: "book_pages"
          #primaryKey: "id"
          #keyType: "int"
          +incrementing: true
          #with: []
          #withCount: []
          +preventsLazyLoading: false
          #perPage: 15
          +exists: true
          +wasRecentlyCreated: false
          #escapeWhenCastingToString: false
          #attributes: array:21 [
            "id" => 1434781
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_page_start" => "140"
            "field_url" => "/9-klass/fizika/gendenshtejn-uchebnik/page-2-140"
            "field_display_title" => "140"
            "field_folder" => "2"
            "field_image_name" => "140"
            "field_branch_parent" => Illuminate\Database\Eloquent\Collection {#1164
              #items: array:1 [
                0 => App\Models\Branch {#1207
                  #connection: "mysql"
                  #table: "branches"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:24 [
                    "id" => 1433262
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => null
                    "field_branch_order" => "2"
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1201 …2}
                    "field_page_start" => "4"
                    "field_branch_display" => "0"
                    "field_branch_expanded" => "0"
                    "field_display_branch_in_title" => "1"
                    "field_display_task_interval" => "0"
                    "field_display_branch_page" => "1"
                    "field_branch_title_in_content" => "0"
                    "field_navigation_title" => null
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "field_branch_cover" => []
                    "field_branch_covers" => []
                    "book" => Illuminate\Database\Eloquent\Collection {#1205 …2}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1166 …2}
                  ]
                  #original: array:24 [
                    "id" => 1433262
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => null
                    "field_branch_order" => "2"
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1201 …2}
                    "field_page_start" => "4"
                    "field_branch_display" => "0"
                    "field_branch_expanded" => "0"
                    "field_display_branch_in_title" => "1"
                    "field_display_task_interval" => "0"
                    "field_display_branch_page" => "1"
                    "field_branch_title_in_content" => "0"
                    "field_navigation_title" => null
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "field_branch_cover" => []
                    "field_branch_covers" => []
                    "book" => Illuminate\Database\Eloquent\Collection {#1205 …2}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1166 …2}
                  ]
                  #changes: []
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                  #dateFormat: null
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                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
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                    0 => "*"
                  ]
                }
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              #escapeWhenCastingToString: false
            }
            "field_weight" => "0"
            "field_book_parent" => Illuminate\Database\Eloquent\Collection {#1161
              #items: array:1 [
                0 => App\Models\Book {#1241}
              ]
              #escapeWhenCastingToString: false
            }
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "edition_groups" => Illuminate\Database\Eloquent\Collection {#1165
              #items: []
              #escapeWhenCastingToString: false
            }
            "content" => Illuminate\Database\Eloquent\Collection {#1153
              #items: array:1 [
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}
№17 (с. 140)
Условие. №17 (с. 140)
скриншот условия
Физика, 9 класс Учебник, авторы: Генденштейн Лев Элевич, Булатова Альбина Александрова, Корнильев Игорь Николаевич, Кошкина Анжелика Васильевна, издательство Бином, Москва, 2016, бирюзового цвета, Часть 1, страница 140, номер 17, Условие

17. Каков знак работы силы трения скольжения при скатывании санок с горы? Сделайте пояснительный рисунок.

Решение. №17 (с. 140)

Работа силы $\text{A}$ определяется как произведение модуля силы $\text{F}$, модуля перемещения $\text{s}$ и косинуса угла $\alpha$ между направлением силы и направлением перемещения. Математически это выражается формулой:$A = F \cdot s \cdot \cos(\alpha)$

Знак работы зависит от угла $\alpha$:

  • Если угол $\alpha$ острый ($0^\circ \le \alpha < 90^\circ$), то $\cos(\alpha) > 0$ и работа $A > 0$ (положительная).
  • Если угол $\alpha$ тупой ($90^\circ < \alpha \le 180^\circ$), то $\cos(\alpha) < 0$ и работа $A < 0$ (отрицательная).
  • Если угол $\alpha$ прямой ($\alpha = 90^\circ$), то $\cos(\alpha) = 0$ и работа $A = 0$.

В случае скатывания санок с горы, вектор перемещения $\vec{s}$ направлен вниз по склону. Сила трения скольжения $\vec{F}_{тр}$ всегда направлена в сторону, противоположную направлению движения. Следовательно, вектор силы трения $\vec{F}_{тр}$ направлен вверх по склону.

Таким образом, угол $\alpha$ между вектором силы трения $\vec{F}_{тр}$ и вектором перемещения $\vec{s}$ составляет $180^\circ$. Так как $\cos(180^\circ) = -1$, работа силы трения скольжения будет отрицательной.$A_{тр} = F_{тр} \cdot s \cdot \cos(180^\circ) = - F_{тр} \cdot s$Отрицательный знак работы означает, что действие силы трения направлено против движения, что приводит к уменьшению механической энергии санок (она переходит в тепловую энергию).

Пояснительный рисунок:

sFтрNmg

Ответ: Знак работы силы трения скольжения при скатывании санок с горы — отрицательный.

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