Номер 3, страница 42 - гдз по физике 9 класс учебник Грачев, Погожев

Физика, 9 класс Учебник, авторы: Грачев Александр Васильевич, Погожев Владимир Александрович, Боков Павел Юрьевич, издательство Вентана-граф, Москва, 2012

Авторы: Грачев А. В., Погожев В. А., Боков П. Ю.

Тип: Учебник

Серия: алгоритм успеха

Издательство: Вентана-граф

Год издания: 2012 - 2026

Цвет обложки: синий изображено здание и радуга

ISBN: 978-5-360-07412-0

Глава 1. Кинематика. Параграф 7. Примеры решения задач на сложение движений - номер 3, страница 42.

App\Models\Task {#1030 // resources/views/models/task/default.blade.php
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                    "breadcrumbs" => array:3 [ …3]
                  ]
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                    "created_at" => "2026-04-10 13:58:26"
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                    "field_tree_default_status" => "tasks"
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                    "field_subject" => Illuminate\Database\Eloquent\Collection {#1080 …2}
                    "field_class" => Illuminate\Database\Eloquent\Collection {#1082 …2}
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1084 …2}
                    "field_author" => Illuminate\Database\Eloquent\Collection {#1086 …2}
                    "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1090 …2}
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1091 …2}
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1093 …2}
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1095 …2}
                    "field_series" => Illuminate\Database\Eloquent\Collection {#1097 …2}
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1099 …2}
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1100 …2}
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1101 …2}
                    "field_publication_number" => "2"
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1103 …2}
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1105 …2}
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                    "field_cover_description" => "изображено здание и радуга"
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                    "field_for_whom" => "Учебник для учащихся общеобразовательных организаций"
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                    "field_tasks_count" => "580"
                    "field_priority" => null
                    "field_default_folder" => "/fizika_09/grachev-u/"
                    "field_isbn" => "978-5-360-07412-0"
                    "field_cover" => array:1 [ …1]
                    "field_cover_alts" => array:1 [ …1]
                    "field_covers" => array:1 [ …1]
                    "field_popular_book" => "0"
                    "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1106 …2}
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1107 …2}
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1108 …2}
                    "field_url" => "/9-klass/fizika/grachev-uchebnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1109 …2}
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "breadcrumbs" => array:3 [ …3]
                  ]
                  #changes: []
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                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
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                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1111
              #items: []
              #escapeWhenCastingToString: false
            }
          ]
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            "id" => 1437875
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Кинематика"
            "field_branch_order" => "1"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1077}
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            "book" => Illuminate\Database\Eloquent\Collection {#1078}
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            0 => "*"
          ]
        }
        1 => App\Models\Branch {#1112
          #connection: "mysql"
          #table: "branches"
          #primaryKey: "id"
          #keyType: "int"
          +incrementing: true
          #with: []
          #withCount: []
          +preventsLazyLoading: false
          #perPage: 15
          +exists: true
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          #escapeWhenCastingToString: false
          #attributes: array:24 [
            "id" => 1437894
            "created_at" => "2026-04-10 13:58:26"
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            "field_branch_order" => "7"
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              #items: array:1 [
                0 => App\Models\Term {#1114
                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
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                  #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: []
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                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
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            "field_page_start" => "37"
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            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1115
              #items: array:1 [
                0 => App\Models\Book {#1116
                  #connection: "mysql"
                  #table: "books"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
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                  #escapeWhenCastingToString: false
                  #attributes: array:50 [
                    "id" => 1202
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                    "field_subject" => Illuminate\Database\Eloquent\Collection {#1117 …2}
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                    "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1127 …2}
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1128 …2}
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1130 …2}
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                    "field_cover" => array:1 [ …1]
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                    "field_for_whom" => "Учебник для учащихся общеобразовательных организаций"
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                    "field_cover" => array:1 [ …1]
                    "field_cover_alts" => array:1 [ …1]
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                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1146 …2}
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                  ]
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              ]
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            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1148
              #items: array:1 [
                0 => App\Models\Branch {#1149
                  #connection: "mysql"
                  #table: "branches"
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                  +incrementing: true
                  #with: []
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                    "book" => Illuminate\Database\Eloquent\Collection {#1152 …2}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1153 …2}
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                    "updated_at" => null
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                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1150 …2}
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                    "book" => Illuminate\Database\Eloquent\Collection {#1152 …2}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1153 …2}
                  ]
                  #changes: []
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                  +timestamps: true
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                  #hidden: []
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                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
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            "created_at" => "2026-04-10 13:58:26"
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            "field_display_title" => "Примеры решения задач на сложение движений"
            "field_branch_order" => "7"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1113}
            "field_page_start" => "37"
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            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1115}
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          ]
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            0 => "*"
          ]
        }
      ]
      #escapeWhenCastingToString: false
    }
    "content" => Illuminate\Database\Eloquent\Collection {#1165
      #items: array:2 [
        0 => App\Models\Element {#1173
          #connection: "mysql"
          #table: "elements"
          #primaryKey: "id"
          #keyType: "int"
          +incrementing: true
          #with: []
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          #attributes: array:7 [
            "id" => 1704979
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1182
              #items: array:1 [
                0 => App\Models\Edition {#1174
                  #connection: "mysql"
                  #table: "editions"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
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                  #escapeWhenCastingToString: false
                  #attributes: array:21 [
                    "id" => 6112
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "title" => "Условие"
                    "field_order" => "1"
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1176 …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 {#1177 …2}
                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1178 …2}
                    "field_process_formula" => "katex"
                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1179 …2}
                    "field_content_source" => null
                  ]
                  #original: array:21 [
                    "id" => 6112
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "title" => "Условие"
                    "field_order" => "1"
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1176 …2}
                    "field_content_type" => "free"
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                    "field_solution_author" => "Автор"
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                    "field_responsible" => Illuminate\Database\Eloquent\Collection {#1177 …2}
                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1178 …2}
                    "field_process_formula" => "katex"
                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1179 …2}
                    "field_content_source" => null
                  ]
                  #changes: []
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                  #hidden: []
                  #visible: []
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                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "task" => array:2 [
              "refs" => "1438091"
              "type" => "task"
            ]
            "text" => "<p><strong>3.</strong> Рыбак плывёт на лодке строго против течения реки. Когда он проплывал под мостом, с лодки упал деревянный багор. Пропажу багра рыбак заметил через 0,5 ч. Он быстро повернул назад. Багор рыбак обнаружил в 5 км от моста. Определите скорость течения реки, считая, что рыбак всё время грёб одинаково.</p>"
            "img" => array:1 [
              0 => array:5 [
                "name" => "3-1.jpg"
                "alt" => null
                "width" => "495"
                "height" => 143
                "path" => "/media/fizika_09/grachev-u/0-07upr/3-1.webp?ts=1759503094"
              ]
            ]
          ]
          #original: array:7 [
            "id" => 1704979
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1182}
            "task" => array:2 [
              "refs" => "1438091"
              "type" => "task"
            ]
            "text" => "<p><strong>3.</strong> Рыбак плывёт на лодке строго против течения реки. Когда он проплывал под мостом, с лодки упал деревянный багор. Пропажу багра рыбак заметил через 0,5 ч. Он быстро повернул назад. Багор рыбак обнаружил в 5 км от моста. Определите скорость течения реки, считая, что рыбак всё время грёб одинаково.</p>"
            "img" => array:1 [
              0 => array:5 [
                "name" => "3-1.jpg"
                "alt" => null
                "width" => "495"
                "height" => 143
                "path" => "/media/fizika_09/grachev-u/0-07upr/3-1.webp?ts=1759503094"
              ]
            ]
          ]
          #changes: []
          #casts: []
          #classCastCache: []
          #attributeCastCache: []
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            0 => "*"
          ]
        }
        1 => App\Models\Element {#1180
          #connection: "mysql"
          #table: "elements"
          #primaryKey: "id"
          #keyType: "int"
          +incrementing: true
          #with: []
          #withCount: []
          +preventsLazyLoading: false
          #perPage: 15
          +exists: true
          +wasRecentlyCreated: false
          #escapeWhenCastingToString: false
          #attributes: array:6 [
            "id" => 1812663
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1190
              #items: array:1 [
                0 => App\Models\Edition {#1181
                  #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" => 6644
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "title" => "Решение"
                    "field_order" => "2"
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1184 …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 {#1185 …2}
                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1186 …2}
                    "field_process_formula" => "katex"
                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1187 …2}
                    "field_content_source" => null
                  ]
                  #original: array:21 [
                    "id" => 6644
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "title" => "Решение"
                    "field_order" => "2"
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1184 …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 {#1185 …2}
                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1186 …2}
                    "field_process_formula" => "katex"
                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1187 …2}
                    "field_content_source" => 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
            }
            "task" => array:2 [
              "refs" => "1438091"
              "type" => "task"
            ]
            "text" => "<p><strong>Дано:</strong></p><p>$t_1 = 0,5$ ч</p><p>$S = 5$ км</p><p><strong>Найти:</strong></p><p>$v_т$</p><p><strong>Решение:</strong></p><p>Для решения этой задачи удобнее всего перейти в систему отсчета, связанную с водой. В этой системе отсчета вода и плывущий по ней багор неподвижны. Мост же удаляется от багра со скоростью течения $v_т$.</p><p>Рыбак, после того как багор упал в воду, продолжал грести против течения. В системе отсчета, связанной с водой, он удалялся от багра со своей собственной скоростью (скоростью относительно воды) $v_л$ в течение времени $t_1 = 0,5$ ч.</p><p>Заметив пропажу, рыбак развернулся и начал грести в обратном направлении. В системе отсчета воды он стал приближаться к неподвижному багру с той же скоростью $v_л$. Так как расстояние и скорость те же, время, которое он затратил на возвращение к багру, $t_2$, будет равно времени, в течение которого он удалялся от него:</p><p>$t_2 = t_1 = 0,5$ ч.</p><p>Таким образом, общее время, которое прошло с момента падения багра до момента, когда рыбак его догнал, составляет:</p><p>$t_{общ} = t_1 + t_2 = 0,5 \text{ ч} + 0,5 \text{ ч} = 1$ ч.</p><p>Теперь вернемся в систему отсчета, связанную с берегом (мостом). В этой системе отсчета багор, упав в воду у моста, плыл по течению в течение всего времени $t_{общ}$. Скорость багра относительно берега равна скорости течения реки $v_т$.</p><p>По условию, за это время багор отплыл от моста на расстояние $S = 5$ км. Зная расстояние и время, мы можем найти скорость течения:</p><p>$v_т = \frac{S}{t_{общ}}$</p><p>Подставим числовые значения:</p><p>$v_т = \frac{5 \text{ км}}{1 \text{ ч}} = 5$ км/ч.</p><p><strong>Ответ:</strong> скорость течения реки равна 5 км/ч.</p>"
          ]
          #original: array:6 [
            "id" => 1812663
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1190}
            "task" => array:2 [
              "refs" => "1438091"
              "type" => "task"
            ]
            "text" => "<p><strong>Дано:</strong></p><p>$t_1 = 0,5$ ч</p><p>$S = 5$ км</p><p><strong>Найти:</strong></p><p>$v_т$</p><p><strong>Решение:</strong></p><p>Для решения этой задачи удобнее всего перейти в систему отсчета, связанную с водой. В этой системе отсчета вода и плывущий по ней багор неподвижны. Мост же удаляется от багра со скоростью течения $v_т$.</p><p>Рыбак, после того как багор упал в воду, продолжал грести против течения. В системе отсчета, связанной с водой, он удалялся от багра со своей собственной скоростью (скоростью относительно воды) $v_л$ в течение времени $t_1 = 0,5$ ч.</p><p>Заметив пропажу, рыбак развернулся и начал грести в обратном направлении. В системе отсчета воды он стал приближаться к неподвижному багру с той же скоростью $v_л$. Так как расстояние и скорость те же, время, которое он затратил на возвращение к багру, $t_2$, будет равно времени, в течение которого он удалялся от него:</p><p>$t_2 = t_1 = 0,5$ ч.</p><p>Таким образом, общее время, которое прошло с момента падения багра до момента, когда рыбак его догнал, составляет:</p><p>$t_{общ} = t_1 + t_2 = 0,5 \text{ ч} + 0,5 \text{ ч} = 1$ ч.</p><p>Теперь вернемся в систему отсчета, связанную с берегом (мостом). В этой системе отсчета багор, упав в воду у моста, плыл по течению в течение всего времени $t_{общ}$. Скорость багра относительно берега равна скорости течения реки $v_т$.</p><p>По условию, за это время багор отплыл от моста на расстояние $S = 5$ км. Зная расстояние и время, мы можем найти скорость течения:</p><p>$v_т = \frac{S}{t_{общ}}$</p><p>Подставим числовые значения:</p><p>$v_т = \frac{5 \text{ км}}{1 \text{ ч}} = 5$ км/ч.</p><p><strong>Ответ:</strong> скорость течения реки равна 5 км/ч.</p>"
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    "book" => Illuminate\Database\Eloquent\Collection {#1207
      #items: array:1 [
        0 => App\Models\Book {#1170
          #connection: "mysql"
          #table: "books"
          #primaryKey: "id"
          #keyType: "int"
          +incrementing: false
          #with: []
          #withCount: []
          +preventsLazyLoading: false
          #perPage: 15
          +exists: true
          +wasRecentlyCreated: false
          #escapeWhenCastingToString: false
          #attributes: array:50 [
            "id" => 1202
            "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 {#1157
              #items: array:1 [
                0 => App\Models\Term {#1156
                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
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                  #perPage: 15
                  +exists: true
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                  #attributes: array:10 [
                    "id" => 6493
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Физика"
                    "field_abbreviated_name" => null
                    "field_cases" => array:6 [ …6]
                    "field_foreign_lang_name" => null
                    "field_short_name" => null
                    "field_subject_type" => "technical_subject"
                    "field_translit" => "fizika"
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                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Физика"
                    "field_abbreviated_name" => null
                    "field_cases" => array:6 [ …6]
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                    "field_translit" => "fizika"
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              #escapeWhenCastingToString: false
            }
            "field_class" => Illuminate\Database\Eloquent\Collection {#1155
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                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:6 [
                    "id" => 5458
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "9"
                    "field_cases" => array:6 [ …6]
                    "field_translit" => "devjatyj"
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                  #original: array:6 [
                    "id" => 5458
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "9"
                    "field_cases" => array:6 [ …6]
                    "field_translit" => "devjatyj"
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                    0 => "*"
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              ]
              #escapeWhenCastingToString: false
            }
            "field_publisher" => Illuminate\Database\Eloquent\Collection {#1161
              #items: array:1 [
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                  #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" => 5174
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Вентана-граф"
                    "field_cases" => null
                    "field_translit" => "ventana-graf"
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                  #original: array:6 [
                    "id" => 5174
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Вентана-граф"
                    "field_cases" => null
                    "field_translit" => "ventana-graf"
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                  +timestamps: true
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                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_author" => Illuminate\Database\Eloquent\Collection {#1158
              #items: array:3 [
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                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
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                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:12 [
                    "id" => 4180
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Грачев"
                    "field_bio" => null
                    "field_degree_rp" => null
                    "field_foreign_lang_name" => null
                    "field_foreign_lang_patronymic" => null
                    "field_foreign_lang_surname" => null
                    "field_name" => "Александр"
                    "field_patronymic" => "Васильевич"
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                  #original: array:12 [
                    "id" => 4180
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Грачев"
                    "field_bio" => null
                    "field_degree_rp" => null
                    "field_foreign_lang_name" => null
                    "field_foreign_lang_patronymic" => null
                    "field_foreign_lang_surname" => null
                    "field_name" => "Александр"
                    "field_patronymic" => "Васильевич"
                    "field_surname_rp" => null
                  ]
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                  #dateFormat: null
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                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
                1 => App\Models\Term {#1164
                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
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                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
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                  #escapeWhenCastingToString: false
                  #attributes: array:12 [
                    "id" => 5484
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Погожев"
                    "field_bio" => null
                    "field_degree_rp" => null
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                    "field_foreign_lang_patronymic" => null
                    "field_foreign_lang_surname" => null
                    "field_name" => "Владимир"
                    "field_patronymic" => "Александрович"
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                    "id" => 5484
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Погожев"
                    "field_bio" => null
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                    "field_foreign_lang_name" => null
                    "field_foreign_lang_patronymic" => null
                    "field_foreign_lang_surname" => null
                    "field_name" => "Владимир"
                    "field_patronymic" => "Александрович"
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                  ]
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                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
                2 => App\Models\Term {#1163
                  #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" => 3888
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Боков"
                    "field_bio" => null
                    "field_degree_rp" => null
                    "field_foreign_lang_name" => null
                    "field_foreign_lang_patronymic" => null
                    "field_foreign_lang_surname" => null
                    "field_name" => "Павел"
                    "field_patronymic" => "Юрьевич"
                    "field_surname_rp" => null
                  ]
                  #original: array:12 [
                    "id" => 3888
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Боков"
                    "field_bio" => null
                    "field_degree_rp" => null
                    "field_foreign_lang_name" => null
                    "field_foreign_lang_patronymic" => null
                    "field_foreign_lang_surname" => null
                    "field_name" => "Павел"
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                  ]
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                  #attributeCastCache: []
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                  #touches: []
                  +timestamps: true
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                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1172
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_book_type" => Illuminate\Database\Eloquent\Collection {#1168
              #items: array:1 [
                0 => App\Models\Term {#1166
                  #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: []
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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
            }
            "field_country" => Illuminate\Database\Eloquent\Collection {#1169
              #items: array:1 [
                0 => App\Models\Term {#1167
                  #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"
                  ]
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                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_city" => Illuminate\Database\Eloquent\Collection {#1188
              #items: array:1 [
                0 => App\Models\Term {#1189
                  #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 {#1191
              #items: array:1 [
                0 => App\Models\Term {#1192
                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:8 [
                    "id" => 4697
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "алгоритм успеха"
                    "field_cases" => null
                    "field_foreign_lang_series" => null
                    "field_transcription_eng" => null
                    "field_translit" => "algoritm uspekha"
                  ]
                  #original: array:8 [
                    "id" => 4697
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "алгоритм успеха"
                    "field_cases" => null
                    "field_foreign_lang_series" => null
                    "field_transcription_eng" => null
                    "field_translit" => "algoritm uspekha"
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_umk" => Illuminate\Database\Eloquent\Collection {#1193
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1194
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1195
              #items: array:1 [
                0 => App\Models\Term {#1196
                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:10 [
                    "id" => 6706
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "ФГОС (старый)"
                    "field_cases" => array:6 [ …6]
                    "field_color" => null
                    "field_end_year" => "2022"
                    "field_start_year" => "2019"
                    "field_translit" => "fgos-old"
                    "field_type" => null
                  ]
                  #original: array:10 [
                    "id" => 6706
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "ФГОС (старый)"
                    "field_cases" => array:6 [ …6]
                    "field_color" => null
                    "field_end_year" => "2022"
                    "field_start_year" => "2019"
                    "field_translit" => "fgos-old"
                    "field_type" => null
                  ]
                  #changes: []
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                  #attributeCastCache: []
                  #dateFormat: null
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                  #relations: []
                  #touches: []
                  +timestamps: true
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                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_publication_number" => "2"
            "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1197
              #items: array:1 [
                0 => App\Models\Term {#1198
                  #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" => 6900
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "доработанное"
                    "field_cases" => array:6 [ …6]
                    "field_translit" => "dorabotannoe"
                  ]
                  #original: array:6 [
                    "id" => 6900
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "доработанное"
                    "field_cases" => array:6 [ …6]
                    "field_translit" => "dorabotannoe"
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
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                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1199
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_under_the_edition_degree" => null
            "field_cover_description" => "изображено здание и радуга"
            "field_publication_year" => "2012"
            "field_publication_year_until" => null
            "field_part" => ""
            "field_part_writing" => ""
            "field_second_foreign_language" => null
            "field_for_whom" => "Учебник для учащихся общеобразовательных организаций"
            "field_allowed" => null
            "field_reserve_field" => null
            "field_link_to_source" => null
            "field_tasks_count" => "580"
            "field_priority" => null
            "field_default_folder" => "/fizika_09/grachev-u/"
            "field_isbn" => "978-5-360-07412-0"
            "field_cover" => array:1 [
              0 => "/media/fizika_09/grachev-u/covers/cover1.webp?ts=1759082140"
            ]
            "field_cover_alts" => array:1 [
              0 => ""
            ]
            "field_covers" => array:1 [
              0 => array:4 [
                "path" => "/media/fizika_09/grachev-u/covers/cover1.webp?ts=1759082140"
                "alt" => ""
                "width" => "2294"
                "height" => "3039"
              ]
            ]
            "field_popular_book" => "0"
            "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1200
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_new_book" => Illuminate\Database\Eloquent\Collection {#1201
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_old_book" => Illuminate\Database\Eloquent\Collection {#1202
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_url" => "/9-klass/fizika/grachev-uchebnik"
            "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1203
              #items: array:1 [
                0 => App\Models\Term {#1204
                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:6 [
                    "id" => 49
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "синий"
                    "field_cases" => array:6 [ …6]
                    "field_translit" => "siniy"
                  ]
                  #original: array:6 [
                    "id" => 49
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "синий"
                    "field_cases" => array:6 [ …6]
                    "field_translit" => "siniy"
                  ]
                  #changes: []
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                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
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                  #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" => 1202
            "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 {#1157}
            "field_class" => Illuminate\Database\Eloquent\Collection {#1155}
            "field_publisher" => Illuminate\Database\Eloquent\Collection {#1161}
            "field_author" => Illuminate\Database\Eloquent\Collection {#1158}
            "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1172}
            "field_book_type" => Illuminate\Database\Eloquent\Collection {#1168}
            "field_country" => Illuminate\Database\Eloquent\Collection {#1169}
            "field_city" => Illuminate\Database\Eloquent\Collection {#1188}
            "field_series" => Illuminate\Database\Eloquent\Collection {#1191}
            "field_umk" => Illuminate\Database\Eloquent\Collection {#1193}
            "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1194}
            "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1195}
            "field_publication_number" => "2"
            "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1197}
            "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1199}
            "field_under_the_edition_degree" => null
            "field_cover_description" => "изображено здание и радуга"
            "field_publication_year" => "2012"
            "field_publication_year_until" => null
            "field_part" => ""
            "field_part_writing" => ""
            "field_second_foreign_language" => null
            "field_for_whom" => "Учебник для учащихся общеобразовательных организаций"
            "field_allowed" => null
            "field_reserve_field" => null
            "field_link_to_source" => null
            "field_tasks_count" => "580"
            "field_priority" => null
            "field_default_folder" => "/fizika_09/grachev-u/"
            "field_isbn" => "978-5-360-07412-0"
            "field_cover" => array:1 [
              0 => "/media/fizika_09/grachev-u/covers/cover1.webp?ts=1759082140"
            ]
            "field_cover_alts" => array:1 [
              0 => ""
            ]
            "field_covers" => array:1 [
              0 => array:4 [
                "path" => "/media/fizika_09/grachev-u/covers/cover1.webp?ts=1759082140"
                "alt" => ""
                "width" => "2294"
                "height" => "3039"
              ]
            ]
            "field_popular_book" => "0"
            "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1200}
            "field_new_book" => Illuminate\Database\Eloquent\Collection {#1201}
            "field_old_book" => Illuminate\Database\Eloquent\Collection {#1202}
            "field_url" => "/9-klass/fizika/grachev-uchebnik"
            "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1203}
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "breadcrumbs" => array:3 [
              "class" => 380
              "subject" => 556
              "class_subject" => 493
            ]
          ]
          #changes: []
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          #classCastCache: []
          #attributeCastCache: []
          #dateFormat: null
          #appends: []
          #dispatchesEvents: []
          #observables: []
          #relations: []
          #touches: []
          +timestamps: true
          +usesUniqueIds: false
          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
      ]
      #escapeWhenCastingToString: false
    }
    "page" => Illuminate\Database\Eloquent\Collection {#1212
      #items: array:1 [
        0 => App\Models\BookPage {#1211
          #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" => 1437548
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_page_start" => "42"
            "field_url" => "/9-klass/fizika/grachev-uchebnik/page-42"
            "field_display_title" => "42"
            "field_folder" => "1"
            "field_image_name" => "42"
            "field_branch_parent" => Illuminate\Database\Eloquent\Collection {#1213
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_weight" => "0"
            "field_book_parent" => Illuminate\Database\Eloquent\Collection {#1214
              #items: array:1 [
                0 => App\Models\Book {#1170}
              ]
              #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 {#1215
              #items: []
              #escapeWhenCastingToString: false
            }
            "content" => Illuminate\Database\Eloquent\Collection {#1225
              #items: array:1 [
                0 => App\Models\Element {#1224
                  #connection: "mysql"
                  #table: "elements"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:6 [
                    "id" => 1705544
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "edition" => Illuminate\Database\Eloquent\Collection {#1226 …2}
                    "book_page" => array:2 [ …2]
                    "img" => array:1 [ …1]
                  ]
                  #original: array:6 [
                    "id" => 1705544
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "edition" => Illuminate\Database\Eloquent\Collection {#1226 …2}
                    "book_page" => array:2 [ …2]
                    "img" => array:1 [ …1]
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "next" => array:2 [
              "refs" => "1437549"
              "type" => "book_page"
            ]
            "previous" => array:2 [
              "refs" => "1437547"
              "type" => "book_page"
            ]
            "tasks" => Illuminate\Database\Eloquent\Collection {#1463
              #items: array:3 [
                0 => App\Models\Task {#1473
                  #connection: "mysql"
                  #table: "tasks"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:24 [
                    "id" => 1438089
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_page_start" => "42"
                    "field_page_end" => null
                    "field_url" => "/9-klass/fizika/grachev-uchebnik/07upr-1"
                    "field_display_title" => "1"
                    "field_outside_task" => null
                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1474 …2}
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "field_match" => null
                    "breadcrumbs" => []
                    "edition_groups" => Illuminate\Database\Eloquent\Collection {#1475 …2}
                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1476 …2}
                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1477 …2}
                    "content" => Illuminate\Database\Eloquent\Collection {#1494 …2}
                    "next" => array:2 [ …2]
                    "previous" => array:2 [ …2]
                    "book" => Illuminate\Database\Eloquent\Collection {#1496 …2}
                    "page" => array:2 [ …2]
                  ]
                  #original: array:24 [
                    "id" => 1438089
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_page_start" => "42"
                    "field_page_end" => null
                    "field_url" => "/9-klass/fizika/grachev-uchebnik/07upr-1"
                    "field_display_title" => "1"
                    "field_outside_task" => null
                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1474 …2}
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№3 (с. 42)
Условие. №3 (с. 42)
скриншот условия
Физика, 9 класс Учебник, авторы: Грачев Александр Васильевич, Погожев Владимир Александрович, Боков Павел Юрьевич, издательство Вентана-граф, Москва, 2012, страница 42, номер 3, Условие

3. Рыбак плывёт на лодке строго против течения реки. Когда он проплывал под мостом, с лодки упал деревянный багор. Пропажу багра рыбак заметил через 0,5 ч. Он быстро повернул назад. Багор рыбак обнаружил в 5 км от моста. Определите скорость течения реки, считая, что рыбак всё время грёб одинаково.

Решение. №3 (с. 42)

Дано:

$t_1 = 0,5$ ч

$S = 5$ км

Найти:

$v_т$

Решение:

Для решения этой задачи удобнее всего перейти в систему отсчета, связанную с водой. В этой системе отсчета вода и плывущий по ней багор неподвижны. Мост же удаляется от багра со скоростью течения $v_т$.

Рыбак, после того как багор упал в воду, продолжал грести против течения. В системе отсчета, связанной с водой, он удалялся от багра со своей собственной скоростью (скоростью относительно воды) $v_л$ в течение времени $t_1 = 0,5$ ч.

Заметив пропажу, рыбак развернулся и начал грести в обратном направлении. В системе отсчета воды он стал приближаться к неподвижному багру с той же скоростью $v_л$. Так как расстояние и скорость те же, время, которое он затратил на возвращение к багру, $t_2$, будет равно времени, в течение которого он удалялся от него:

$t_2 = t_1 = 0,5$ ч.

Таким образом, общее время, которое прошло с момента падения багра до момента, когда рыбак его догнал, составляет:

$t_{общ} = t_1 + t_2 = 0,5 \text{ ч} + 0,5 \text{ ч} = 1$ ч.

Теперь вернемся в систему отсчета, связанную с берегом (мостом). В этой системе отсчета багор, упав в воду у моста, плыл по течению в течение всего времени $t_{общ}$. Скорость багра относительно берега равна скорости течения реки $v_т$.

По условию, за это время багор отплыл от моста на расстояние $S = 5$ км. Зная расстояние и время, мы можем найти скорость течения:

$v_т = \frac{S}{t_{общ}}$

Подставим числовые значения:

$v_т = \frac{5 \text{ км}}{1 \text{ ч}} = 5$ км/ч.

Ответ: скорость течения реки равна 5 км/ч.

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