Номер 149, страница 268 - 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

Электродинамика. Электромагнитные колебания и волны. 38. Элементы теории относительности. Олимпиадные задачи - номер 149, страница 268.

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                            "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 {#1128
                      #items: array:1 [
                        0 => App\Models\Term {#1129
                          #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 {#1130
                      #items: array:3 [
                        0 => App\Models\Term {#1131
                          #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 {#1132
                          #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 {#1133
                          #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 {#1134
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1135
                      #items: array:1 [
                        0 => App\Models\Term {#1136
                          #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 {#1137
                      #items: array:1 [
                        0 => App\Models\Term {#1138
                          #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 {#1139
                      #items: array:1 [
                        0 => App\Models\Term {#1140
                          #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 {#1141
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1142
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1143
                      #items: array:1 [
                        0 => App\Models\Term {#1144
                          #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 {#1145
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_publication_number" => null
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1146
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1147
                      #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 {#1148
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1149
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1150
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_url" => "/10-klass/fizika/gelfgat-zadachnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1151
                      #items: array:1 [
                        0 => App\Models\Term {#1152
                          #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 {#1124}
                    "field_class" => Illuminate\Database\Eloquent\Collection {#1125}
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1128}
                    "field_author" => Illuminate\Database\Eloquent\Collection {#1130}
                    "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1134}
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1135}
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1137}
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1139}
                    "field_series" => Illuminate\Database\Eloquent\Collection {#1141}
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1142}
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1143}
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1145}
                    "field_publication_number" => null
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1146}
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1147}
                    "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 {#1148}
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1149}
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1150}
                    "field_url" => "/10-klass/fizika/gelfgat-zadachnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1151}
                    "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 {#1153
              #items: []
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1319339
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Электродинамика"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1121}
            "field_page_start" => "163"
            "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 {#1155}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1153}
          ]
          #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 {#1154
          #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" => 1319371
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Электромагнитные колебания и волны"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1156
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "241"
            "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 {#1157
              #items: array:1 [
                0 => App\Models\Book {#1122}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1158
              #items: array:1 [
                0 => App\Models\Branch {#1034}
              ]
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1319371
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Электромагнитные колебания и волны"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1156}
            "field_page_start" => "241"
            "field_branch_display" => "0"
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            "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 {#1157}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1158}
          ]
          #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 {#1159
          #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" => 1319383
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "38. Элементы теории относительности"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1160
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "265"
            "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 {#1161
              #items: array:1 [
                0 => App\Models\Book {#1122}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1170
              #items: array:1 [
                0 => App\Models\Branch {#1169
                  #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" => 1319371
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Электромагнитные колебания и волны"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1171
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_page_start" => "241"
                    "field_branch_display" => "0"
                    "field_branch_expanded" => "0"
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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 {#1172
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1173
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                  ]
                  #original: array:24 [
                    "id" => 1319371
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Электромагнитные колебания и волны"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1171}
                    "field_page_start" => "241"
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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
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                    "field_branch_covers" => []
                    "book" => Illuminate\Database\Eloquent\Collection {#1172}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1173}
                  ]
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                  #attributeCastCache: []
                  #dateFormat: null
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                  #dispatchesEvents: []
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                  #touches: []
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                  #hidden: []
                  #visible: []
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                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1319383
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "38. Элементы теории относительности"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1160}
            "field_page_start" => "265"
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            "field_display_branch_in_title" => "1"
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            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1161}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1170}
          ]
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          #attributeCastCache: []
          #dateFormat: null
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          #touches: []
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          #visible: []
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          #guarded: array:1 [
            0 => "*"
          ]
        }
        3 => App\Models\Branch {#1163
          #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" => 1319385
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Олимпиадные задачи"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1162
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "267"
            "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 {#1166
              #items: array:1 [
                0 => App\Models\Book {#1122}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1179
              #items: array:1 [
                0 => App\Models\Branch {#1178
                  #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" => 1319383
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "38. Элементы теории относительности"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1180
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_page_start" => "265"
                    "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 {#1181
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1182
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                  ]
                  #original: array:24 [
                    "id" => 1319383
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "38. Элементы теории относительности"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1180}
                    "field_page_start" => "265"
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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 {#1181}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1182}
                  ]
                  #changes: []
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                  #attributeCastCache: []
                  #dateFormat: null
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                  #dispatchesEvents: []
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                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1319385
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Олимпиадные задачи"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1162}
            "field_page_start" => "267"
            "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 {#1166}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1179}
          ]
          #changes: []
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          #attributeCastCache: []
          #dateFormat: null
          #appends: []
          #dispatchesEvents: []
          #observables: []
          #relations: []
          #touches: []
          +timestamps: true
          +usesUniqueIds: false
          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
      ]
      #escapeWhenCastingToString: false
    }
    "content" => Illuminate\Database\Eloquent\Collection {#1072
      #items: array:2 [
        0 => App\Models\Element {#1101
          #connection: "mysql"
          #table: "elements"
          #primaryKey: "id"
          #keyType: "int"
          +incrementing: true
          #with: []
          #withCount: []
          +preventsLazyLoading: false
          #perPage: 15
          +exists: true
          +wasRecentlyCreated: false
          #escapeWhenCastingToString: false
          #attributes: array:7 [
            "id" => 1494127
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1091
              #items: array:1 [
                0 => App\Models\Edition {#1100
                  #connection: "mysql"
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            "text" => "<p><strong>О49.</strong> Какое расстояние $\text{s}$ должен пройти электрон (см. задачу О48), чтобы приобрести скорость $\text{v}$? Запишите формулу зависимости $s(t)$.</p><p><strong>Решение.</strong> Согласно закону сохранения энергии$\frac{mc^2}{\sqrt{1-v^2/c^2}} = mc^2 + A$, где $A = Fs = eEs$ — работа электрического поля.</p><p>Отсюда $s = \frac{mc^2}{eE} \left( \frac{1}{\sqrt{1-v^2/c^2}} - 1 \right)$. Подставляя в это выражение формулу для $\text{v}$ (см. задачу О48), получаем$s = \frac{c}{eE} \left(\sqrt{m^2c^2 + e^2E^2t^2} - mc\right)$.</p>"
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                "path" => "/media/fizika_10/gelfgat-z/0-olimp/149-1.webp?ts=1756251279"
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            "id" => 1494127
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1091}
            "task" => array:2 [
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              "type" => "task"
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            "text" => "<p><strong>О49.</strong> Какое расстояние $\text{s}$ должен пройти электрон (см. задачу О48), чтобы приобрести скорость $\text{v}$? Запишите формулу зависимости $s(t)$.</p><p><strong>Решение.</strong> Согласно закону сохранения энергии$\frac{mc^2}{\sqrt{1-v^2/c^2}} = mc^2 + A$, где $A = Fs = eEs$ — работа электрического поля.</p><p>Отсюда $s = \frac{mc^2}{eE} \left( \frac{1}{\sqrt{1-v^2/c^2}} - 1 \right)$. Подставляя в это выражение формулу для $\text{v}$ (см. задачу О48), получаем$s = \frac{c}{eE} \left(\sqrt{m^2c^2 + e^2E^2t^2} - mc\right)$.</p>"
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            "text" => "<p><strong>Дано:</strong></p><p>$m$ - масса покоя электрона,</p><p>$e$ - элементарный заряд (модуль заряда электрона),</p><p>$c$ - скорость света в вакууме,</p><p>$E$ - напряженность однородного электрического поля,</p><p>$v_0 = 0$ - начальная скорость электрона.</p><p><strong>Найти:</strong></p><p><strong>1.</strong> $s(v)$ - расстояние как функция скорости.</p><p><strong>2.</strong> $s(t)$ - расстояние как функция времени.</p><p><strong>Решение</strong></p><p><strong>Какое расстояние s должен пройти электрон, чтобы приобрести скорость v?</strong></p><p>Для решения задачи воспользуемся теоремой об изменении энергии в релятивистском случае. Работа, совершаемая электрическим полем над электроном, идет на увеличение его полной энергии. Предполагается, что начальная скорость электрона равна нулю, следовательно, его начальная энергия равна энергии покоя $E_0 = mc^2$.</p><p>Полная энергия электрона, движущегося со скоростью $v$, определяется формулой:</p><p>$E_{полн} = \frac{mc^2}{\sqrt{1 - v^2/c^2}}$</p><p>Работа $A$, совершаемая силой $F = eE$ однородного электрического поля на пути $s$, равна:</p><p>$A = F \cdot s = eEs$</p><p>Согласно закону сохранения энергии, изменение энергии равно совершенной работе:</p><p>$E_{полн} - E_0 = A$</p><p>Подставим выражения для энергий и работы в это уравнение:</p><p>$\frac{mc^2}{\sqrt{1 - v^2/c^2}} - mc^2 = eEs$</p><p>Выразим из этого уравнения расстояние $s$:</p><p>$s = \frac{1}{eE} \left( \frac{mc^2}{\sqrt{1 - v^2/c^2}} - mc^2 \right)$</p><p>Вынесем $mc^2$ за скобки, чтобы получить выражение, как в задачнике:</p><p>$s = \frac{mc^2}{eE} \left( \frac{1}{\sqrt{1 - v^2/c^2}} - 1 \right)$</p><p><strong>Ответ:</strong> $s = \frac{mc^2}{eE} \left( \frac{1}{\sqrt{1 - v^2/c^2}} - 1 \right)$</p><p><strong>Запишите формулу зависимости s(t).</strong></p><p>Чтобы получить зависимость $s(t)$, необходимо найти, как скорость $v$ зависит от времени $t$, а затем подставить это выражение в полученную выше формулу для $s$. Зависимость $v(t)$ найдем из релятивистского второго закона Ньютона:</p><p>$\frac{d\vec{p}}{dt} = \vec{F}$</p><p>где $\vec{p} = \frac{m\vec{v}}{\sqrt{1 - v^2/c^2}}$ - релятивистский импульс, а $\vec{F} = e\vec{E}$ - сила, действующая на электрон.</p><p>Поскольку сила постоянна и направлена вдоль одной оси, движение будет прямолинейным. В скалярной форме уравнение выглядит так:</p><p>$\frac{d}{dt}\left(\frac{mv}{\sqrt{1 - v^2/c^2}}\right) = eE$</p><p>Интегрируя обе части по времени от $0$ до $t$ (учитывая, что при $t=0$, $v=0$ и $p=0$), получаем:</p><p>$\frac{mv}{\sqrt{1 - v^2/c^2}} = eEt$</p><p>Теперь выразим из этого уравнения скорость $v$. Для этого возведем обе части в квадрат:</p><p>$\frac{m^2v^2}{1 - v^2/c^2} = (eEt)^2$</p><p>$m^2v^2 = (eEt)^2(1 - v^2/c^2)$</p><p>$m^2v^2 + \frac{(eEt)^2}{c^2}v^2 = (eEt)^2$</p><p>$v^2\left(m^2 + \frac{e^2E^2t^2}{c^2}\right) = e^2E^2t^2$</p><p>$v^2 = \frac{e^2E^2t^2c^2}{m^2c^2 + e^2E^2t^2} \implies v(t) = \frac{eEtc}{\sqrt{m^2c^2 + e^2E^2t^2}}$</p><p>Теперь необходимо подставить это выражение для $v$ в формулу для $s$. Удобнее сначала найти релятивистский фактор:</p><p>$1 - \frac{v^2}{c^2} = 1 - \frac{e^2E^2t^2}{m^2c^2 + e^2E^2t^2} = \frac{m^2c^2 + e^2E^2t^2 - e^2E^2t^2}{m^2c^2 + e^2E^2t^2} = \frac{m^2c^2}{m^2c^2 + e^2E^2t^2}$</p><p>Тогда:</p><p>$\frac{1}{\sqrt{1 - v^2/c^2}} = \sqrt{\frac{m^2c^2 + e^2E^2t^2}{m^2c^2}} = \frac{\sqrt{m^2c^2 + e^2E^2t^2}}{mc}$</p><p>Подставляем это в формулу для $s$:</p><p>$s = \frac{mc^2}{eE} \left( \frac{\sqrt{m^2c^2 + e^2E^2t^2}}{mc} - 1 \right)$</p><p>Упрощая, получаем окончательное выражение для $s(t)$:</p><p>$s = \frac{mc^2}{eE} \cdot \frac{\sqrt{m^2c^2 + e^2E^2t^2} - mc}{mc} = \frac{c}{eE} \left( \sqrt{m^2c^2 + e^2E^2t^2} - mc \right)$</p><p><strong>Ответ:</strong> $s(t) = \frac{c}{eE} \left( \sqrt{m^2c^2 + e^2E^2t^2} - mc \right)$</p>"
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            "text" => "<p><strong>Дано:</strong></p><p>$m$ - масса покоя электрона,</p><p>$e$ - элементарный заряд (модуль заряда электрона),</p><p>$c$ - скорость света в вакууме,</p><p>$E$ - напряженность однородного электрического поля,</p><p>$v_0 = 0$ - начальная скорость электрона.</p><p><strong>Найти:</strong></p><p><strong>1.</strong> $s(v)$ - расстояние как функция скорости.</p><p><strong>2.</strong> $s(t)$ - расстояние как функция времени.</p><p><strong>Решение</strong></p><p><strong>Какое расстояние s должен пройти электрон, чтобы приобрести скорость v?</strong></p><p>Для решения задачи воспользуемся теоремой об изменении энергии в релятивистском случае. Работа, совершаемая электрическим полем над электроном, идет на увеличение его полной энергии. Предполагается, что начальная скорость электрона равна нулю, следовательно, его начальная энергия равна энергии покоя $E_0 = mc^2$.</p><p>Полная энергия электрона, движущегося со скоростью $v$, определяется формулой:</p><p>$E_{полн} = \frac{mc^2}{\sqrt{1 - v^2/c^2}}$</p><p>Работа $A$, совершаемая силой $F = eE$ однородного электрического поля на пути $s$, равна:</p><p>$A = F \cdot s = eEs$</p><p>Согласно закону сохранения энергии, изменение энергии равно совершенной работе:</p><p>$E_{полн} - E_0 = A$</p><p>Подставим выражения для энергий и работы в это уравнение:</p><p>$\frac{mc^2}{\sqrt{1 - v^2/c^2}} - mc^2 = eEs$</p><p>Выразим из этого уравнения расстояние $s$:</p><p>$s = \frac{1}{eE} \left( \frac{mc^2}{\sqrt{1 - v^2/c^2}} - mc^2 \right)$</p><p>Вынесем $mc^2$ за скобки, чтобы получить выражение, как в задачнике:</p><p>$s = \frac{mc^2}{eE} \left( \frac{1}{\sqrt{1 - v^2/c^2}} - 1 \right)$</p><p><strong>Ответ:</strong> $s = \frac{mc^2}{eE} \left( \frac{1}{\sqrt{1 - v^2/c^2}} - 1 \right)$</p><p><strong>Запишите формулу зависимости s(t).</strong></p><p>Чтобы получить зависимость $s(t)$, необходимо найти, как скорость $v$ зависит от времени $t$, а затем подставить это выражение в полученную выше формулу для $s$. Зависимость $v(t)$ найдем из релятивистского второго закона Ньютона:</p><p>$\frac{d\vec{p}}{dt} = \vec{F}$</p><p>где $\vec{p} = \frac{m\vec{v}}{\sqrt{1 - v^2/c^2}}$ - релятивистский импульс, а $\vec{F} = e\vec{E}$ - сила, действующая на электрон.</p><p>Поскольку сила постоянна и направлена вдоль одной оси, движение будет прямолинейным. В скалярной форме уравнение выглядит так:</p><p>$\frac{d}{dt}\left(\frac{mv}{\sqrt{1 - v^2/c^2}}\right) = eE$</p><p>Интегрируя обе части по времени от $0$ до $t$ (учитывая, что при $t=0$, $v=0$ и $p=0$), получаем:</p><p>$\frac{mv}{\sqrt{1 - v^2/c^2}} = eEt$</p><p>Теперь выразим из этого уравнения скорость $v$. Для этого возведем обе части в квадрат:</p><p>$\frac{m^2v^2}{1 - v^2/c^2} = (eEt)^2$</p><p>$m^2v^2 = (eEt)^2(1 - v^2/c^2)$</p><p>$m^2v^2 + \frac{(eEt)^2}{c^2}v^2 = (eEt)^2$</p><p>$v^2\left(m^2 + \frac{e^2E^2t^2}{c^2}\right) = e^2E^2t^2$</p><p>$v^2 = \frac{e^2E^2t^2c^2}{m^2c^2 + e^2E^2t^2} \implies v(t) = \frac{eEtc}{\sqrt{m^2c^2 + e^2E^2t^2}}$</p><p>Теперь необходимо подставить это выражение для $v$ в формулу для $s$. Удобнее сначала найти релятивистский фактор:</p><p>$1 - \frac{v^2}{c^2} = 1 - \frac{e^2E^2t^2}{m^2c^2 + e^2E^2t^2} = \frac{m^2c^2 + e^2E^2t^2 - e^2E^2t^2}{m^2c^2 + e^2E^2t^2} = \frac{m^2c^2}{m^2c^2 + e^2E^2t^2}$</p><p>Тогда:</p><p>$\frac{1}{\sqrt{1 - v^2/c^2}} = \sqrt{\frac{m^2c^2 + e^2E^2t^2}{m^2c^2}} = \frac{\sqrt{m^2c^2 + e^2E^2t^2}}{mc}$</p><p>Подставляем это в формулу для $s$:</p><p>$s = \frac{mc^2}{eE} \left( \frac{\sqrt{m^2c^2 + e^2E^2t^2}}{mc} - 1 \right)$</p><p>Упрощая, получаем окончательное выражение для $s(t)$:</p><p>$s = \frac{mc^2}{eE} \cdot \frac{\sqrt{m^2c^2 + e^2E^2t^2} - mc}{mc} = \frac{c}{eE} \left( \sqrt{m^2c^2 + e^2E^2t^2} - mc \right)$</p><p><strong>Ответ:</strong> $s(t) = \frac{c}{eE} \left( \sqrt{m^2c^2 + e^2E^2t^2} - mc \right)$</p>"
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№149 (с. 268)
Условие. №149 (с. 268)
скриншот условия
Физика, 10-11 класс Задачник, авторы: Гельфгат Илья Маркович, Генденштейн Лев Элевич, Кирик Леонид Анатольевич, издательство Илекса, Москва, 2008, красного цвета, страница 268, номер 149, Условие

О49. Какое расстояние $\text{s}$ должен пройти электрон (см. задачу О48), чтобы приобрести скорость $\text{v}$? Запишите формулу зависимости $s(t)$.

Решение. Согласно закону сохранения энергии$\frac{mc^2}{\sqrt{1-v^2/c^2}} = mc^2 + A$, где $A = Fs = eEs$ — работа электрического поля.

Отсюда $s = \frac{mc^2}{eE} \left( \frac{1}{\sqrt{1-v^2/c^2}} - 1 \right)$. Подставляя в это выражение формулу для $\text{v}$ (см. задачу О48), получаем$s = \frac{c}{eE} \left(\sqrt{m^2c^2 + e^2E^2t^2} - mc\right)$.

Решение. №149 (с. 268)

Дано:

$m$ - масса покоя электрона,

$e$ - элементарный заряд (модуль заряда электрона),

$c$ - скорость света в вакууме,

$E$ - напряженность однородного электрического поля,

$v_0 = 0$ - начальная скорость электрона.

Найти:

1. $s(v)$ - расстояние как функция скорости.

2. $s(t)$ - расстояние как функция времени.

Решение

Какое расстояние s должен пройти электрон, чтобы приобрести скорость v?

Для решения задачи воспользуемся теоремой об изменении энергии в релятивистском случае. Работа, совершаемая электрическим полем над электроном, идет на увеличение его полной энергии. Предполагается, что начальная скорость электрона равна нулю, следовательно, его начальная энергия равна энергии покоя $E_0 = mc^2$.

Полная энергия электрона, движущегося со скоростью $v$, определяется формулой:

$E_{полн} = \frac{mc^2}{\sqrt{1 - v^2/c^2}}$

Работа $A$, совершаемая силой $F = eE$ однородного электрического поля на пути $s$, равна:

$A = F \cdot s = eEs$

Согласно закону сохранения энергии, изменение энергии равно совершенной работе:

$E_{полн} - E_0 = A$

Подставим выражения для энергий и работы в это уравнение:

$\frac{mc^2}{\sqrt{1 - v^2/c^2}} - mc^2 = eEs$

Выразим из этого уравнения расстояние $s$:

$s = \frac{1}{eE} \left( \frac{mc^2}{\sqrt{1 - v^2/c^2}} - mc^2 \right)$

Вынесем $mc^2$ за скобки, чтобы получить выражение, как в задачнике:

$s = \frac{mc^2}{eE} \left( \frac{1}{\sqrt{1 - v^2/c^2}} - 1 \right)$

Ответ: $s = \frac{mc^2}{eE} \left( \frac{1}{\sqrt{1 - v^2/c^2}} - 1 \right)$

Запишите формулу зависимости s(t).

Чтобы получить зависимость $s(t)$, необходимо найти, как скорость $v$ зависит от времени $t$, а затем подставить это выражение в полученную выше формулу для $s$. Зависимость $v(t)$ найдем из релятивистского второго закона Ньютона:

$\frac{d\vec{p}}{dt} = \vec{F}$

где $\vec{p} = \frac{m\vec{v}}{\sqrt{1 - v^2/c^2}}$ - релятивистский импульс, а $\vec{F} = e\vec{E}$ - сила, действующая на электрон.

Поскольку сила постоянна и направлена вдоль одной оси, движение будет прямолинейным. В скалярной форме уравнение выглядит так:

$\frac{d}{dt}\left(\frac{mv}{\sqrt{1 - v^2/c^2}}\right) = eE$

Интегрируя обе части по времени от $0$ до $t$ (учитывая, что при $t=0$, $v=0$ и $p=0$), получаем:

$\frac{mv}{\sqrt{1 - v^2/c^2}} = eEt$

Теперь выразим из этого уравнения скорость $v$. Для этого возведем обе части в квадрат:

$\frac{m^2v^2}{1 - v^2/c^2} = (eEt)^2$

$m^2v^2 = (eEt)^2(1 - v^2/c^2)$

$m^2v^2 + \frac{(eEt)^2}{c^2}v^2 = (eEt)^2$

$v^2\left(m^2 + \frac{e^2E^2t^2}{c^2}\right) = e^2E^2t^2$

$v^2 = \frac{e^2E^2t^2c^2}{m^2c^2 + e^2E^2t^2} \implies v(t) = \frac{eEtc}{\sqrt{m^2c^2 + e^2E^2t^2}}$

Теперь необходимо подставить это выражение для $v$ в формулу для $s$. Удобнее сначала найти релятивистский фактор:

$1 - \frac{v^2}{c^2} = 1 - \frac{e^2E^2t^2}{m^2c^2 + e^2E^2t^2} = \frac{m^2c^2 + e^2E^2t^2 - e^2E^2t^2}{m^2c^2 + e^2E^2t^2} = \frac{m^2c^2}{m^2c^2 + e^2E^2t^2}$

Тогда:

$\frac{1}{\sqrt{1 - v^2/c^2}} = \sqrt{\frac{m^2c^2 + e^2E^2t^2}{m^2c^2}} = \frac{\sqrt{m^2c^2 + e^2E^2t^2}}{mc}$

Подставляем это в формулу для $s$:

$s = \frac{mc^2}{eE} \left( \frac{\sqrt{m^2c^2 + e^2E^2t^2}}{mc} - 1 \right)$

Упрощая, получаем окончательное выражение для $s(t)$:

$s = \frac{mc^2}{eE} \cdot \frac{\sqrt{m^2c^2 + e^2E^2t^2} - mc}{mc} = \frac{c}{eE} \left( \sqrt{m^2c^2 + e^2E^2t^2} - mc \right)$

Ответ: $s(t) = \frac{c}{eE} \left( \sqrt{m^2c^2 + e^2E^2t^2} - mc \right)$

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