Номер 3.17, страница 17 - гдз по физике 9 класс задачник Артеменков, Ломаченков

Физика, 9 класс Задачник, авторы: Артеменков Денис Александрович, Ломаченков Иван Алексеевич, Панебратцев Юрий Анатольевич, издательство Просвещение, Москва, 2011

Авторы: Артеменков Д. А., Ломаченков И. А., Панебратцев Ю. А.

Тип: Задачник

Серия: сферы

Издательство: Просвещение

Год издания: 2011 - 2026

Цвет обложки: синий

ISBN: 978-5-09-038216-8

III. Звук - номер 3.17, страница 17.

App\Models\Task {#1030 // resources/views/models/task/default.blade.php
  #connection: "mysql"
  #table: "tasks"
  #primaryKey: "id"
  #keyType: "int"
  +incrementing: true
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  #perPage: 15
  +exists: true
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  #escapeWhenCastingToString: false
  #attributes: array:24 [
    "id" => 1424166
    "created_at" => "2026-04-10 13:58:26"
    "updated_at" => null
    "field_page_start" => "17"
    "field_page_end" => null
    "field_url" => "/9-klass/fizika/artemenkov-zadachnik/3-17"
    "field_display_title" => "3.17"
    "field_outside_task" => null
    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1037
      #items: array:1 [
        0 => App\Models\Term {#1036
          #connection: "mysql"
          #table: "terms"
          #primaryKey: "id"
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          #attributes: array:6 [
            "id" => 26
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "name" => "номер"
            "field_cases" => array:6 [
              "field_accusative_case" => "номер"
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              "field_genitive_case" => "номера"
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            ]
            "field_short_name" => ""
          ]
          #original: array:6 [
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            "updated_at" => null
            "name" => "номер"
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            0 => "*"
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    "edition_groups" => Illuminate\Database\Eloquent\Collection {#1035
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    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1046
      #items: array:1 [
        0 => App\Models\Branch {#1045
          #connection: "mysql"
          #table: "branches"
          #primaryKey: "id"
          #keyType: "int"
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          #attributes: array:24 [
            "id" => 1424066
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            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1047
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              #items: array:1 [
                0 => App\Models\Book {#1048
                  #connection: "mysql"
                  #table: "books"
                  #primaryKey: "id"
                  #keyType: "int"
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                  #attributes: array:50 [
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                        0 => App\Models\Term {#1049
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                            "id" => 6493
                            "created_at" => "2026-04-10 13:58:26"
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                    "field_class" => Illuminate\Database\Eloquent\Collection {#1051
                      #items: array:1 [
                        0 => App\Models\Term {#1052
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
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                          #attributes: array:6 [
                            "id" => 5458
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
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                              "field_creative_case" => "девятым"
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                          ]
                          #original: array:6 [
                            "id" => 5153
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
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                            "field_translit" => "prosveschenie"
                          ]
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                    "field_author" => Illuminate\Database\Eloquent\Collection {#1055
                      #items: array:3 [
                        0 => App\Models\Term {#1056
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                          #table: "terms"
                          #primaryKey: "id"
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                          #attributes: array:12 [
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                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
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                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
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                        1 => App\Models\Term {#1057
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
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        }
        1 => App\Models\Element {#1092
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            "created_at" => "2026-04-10 13:58:26"
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                  #attributes: array:21 [
                    "id" => 6166
                    "created_at" => "2026-04-10 13:58:26"
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                    "title" => "Решение"
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            "text" => "<p><strong>Дано:</strong></p><p>$t_1 = 2 \text{ с}$</p><p>$t_2 = 2 \text{ мин } 18 \text{ с}$</p><p>$v_{звука} = 340 \text{ м/с}$</p><p>Перевод в систему СИ:</p><p>$t_2 = 2 \cdot 60 + 18 = 138 \text{ с}$</p><p><strong>Найти:</strong></p><p>$v_{вел}$ - скорость велосипедиста.</p><p><strong>Решение:</strong></p><p>Примем за начало отсчета ($t=0$) момент, когда велосипедист увидел удар. Пусть в этот момент расстояние между ним и человеком, ударившим по рельсу, было равно $S$. Велосипедист движется навстречу источнику звука.</p><p>Звук и велосипедист движутся навстречу друг другу. Они встретятся через время $t_1 = 2 \text{ с}$. За это время велосипедист проедет расстояние $S_1 = v_{вел} \cdot t_1$, а звук пройдет расстояние $S_2 = v_{звука} \cdot t_1$. Сумма этих расстояний равна начальному расстоянию $S$:</p><p>$S = S_1 + S_2 = v_{вел} \cdot t_1 + v_{звука} \cdot t_1 = (v_{вел} + v_{звука}) \cdot t_1$</p><p>С другой стороны, велосипедист преодолел все начальное расстояние $S$ за общее время $t_2$, двигаясь с постоянной скоростью $v_{вел}$. Следовательно, это расстояние также равно:</p><p>$S = v_{вел} \cdot t_2$</p><p>Поскольку левые части обоих выражений для $S$ равны, мы можем приравнять их правые части:</p><p>$(v_{вел} + v_{звука}) \cdot t_1 = v_{вел} \cdot t_2$</p><p>Теперь решим это уравнение относительно искомой скорости велосипедиста $v_{вел}$:</p><p>$v_{вел} \cdot t_1 + v_{звука} \cdot t_1 = v_{вел} \cdot t_2$</p><p>$v_{звука} \cdot t_1 = v_{вел} \cdot t_2 - v_{вел} \cdot t_1$</p><p>$v_{звука} \cdot t_1 = v_{вел} \cdot (t_2 - t_1)$</p><p>Отсюда выражаем $v_{вел}$:</p><p>$v_{вел} = \frac{v_{звука} \cdot t_1}{t_2 - t_1}$</p><p>Подставим числовые значения из условия задачи:</p><p>$v_{вел} = \frac{340 \text{ м/с} \cdot 2 \text{ с}}{138 \text{ с} - 2 \text{ с}} = \frac{680 \text{ м}}{136 \text{ с}} = 5 \text{ м/с}$</p><p><strong>Ответ:</strong> скорость велосипедиста равна $5 \text{ м/с}$.</p>"
          ]
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            "id" => 1695326
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1102}
            "task" => array:2 [
              "refs" => "1424166"
              "type" => "task"
            ]
            "text" => "<p><strong>Дано:</strong></p><p>$t_1 = 2 \text{ с}$</p><p>$t_2 = 2 \text{ мин } 18 \text{ с}$</p><p>$v_{звука} = 340 \text{ м/с}$</p><p>Перевод в систему СИ:</p><p>$t_2 = 2 \cdot 60 + 18 = 138 \text{ с}$</p><p><strong>Найти:</strong></p><p>$v_{вел}$ - скорость велосипедиста.</p><p><strong>Решение:</strong></p><p>Примем за начало отсчета ($t=0$) момент, когда велосипедист увидел удар. Пусть в этот момент расстояние между ним и человеком, ударившим по рельсу, было равно $S$. Велосипедист движется навстречу источнику звука.</p><p>Звук и велосипедист движутся навстречу друг другу. Они встретятся через время $t_1 = 2 \text{ с}$. За это время велосипедист проедет расстояние $S_1 = v_{вел} \cdot t_1$, а звук пройдет расстояние $S_2 = v_{звука} \cdot t_1$. Сумма этих расстояний равна начальному расстоянию $S$:</p><p>$S = S_1 + S_2 = v_{вел} \cdot t_1 + v_{звука} \cdot t_1 = (v_{вел} + v_{звука}) \cdot t_1$</p><p>С другой стороны, велосипедист преодолел все начальное расстояние $S$ за общее время $t_2$, двигаясь с постоянной скоростью $v_{вел}$. Следовательно, это расстояние также равно:</p><p>$S = v_{вел} \cdot t_2$</p><p>Поскольку левые части обоих выражений для $S$ равны, мы можем приравнять их правые части:</p><p>$(v_{вел} + v_{звука}) \cdot t_1 = v_{вел} \cdot t_2$</p><p>Теперь решим это уравнение относительно искомой скорости велосипедиста $v_{вел}$:</p><p>$v_{вел} \cdot t_1 + v_{звука} \cdot t_1 = v_{вел} \cdot t_2$</p><p>$v_{звука} \cdot t_1 = v_{вел} \cdot t_2 - v_{вел} \cdot t_1$</p><p>$v_{звука} \cdot t_1 = v_{вел} \cdot (t_2 - t_1)$</p><p>Отсюда выражаем $v_{вел}$:</p><p>$v_{вел} = \frac{v_{звука} \cdot t_1}{t_2 - t_1}$</p><p>Подставим числовые значения из условия задачи:</p><p>$v_{вел} = \frac{340 \text{ м/с} \cdot 2 \text{ с}}{138 \text{ с} - 2 \text{ с}} = \frac{680 \text{ м}}{136 \text{ с}} = 5 \text{ м/с}$</p><p><strong>Ответ:</strong> скорость велосипедиста равна $5 \text{ м/с}$.</p>"
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    "page" => Illuminate\Database\Eloquent\Collection {#1043
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            "created_at" => "2026-04-10 13:58:26"
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            "field_page_start" => "17"
            "field_url" => "/9-klass/fizika/artemenkov-zadachnik/page-17"
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            "field_book_parent" => Illuminate\Database\Eloquent\Collection {#1101
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            "content" => Illuminate\Database\Eloquent\Collection {#1113
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                0 => App\Models\Element {#1112
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                    "created_at" => "2026-04-10 13:58:26"
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                    "edition" => Illuminate\Database\Eloquent\Collection {#1114
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                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "edition" => Illuminate\Database\Eloquent\Collection {#1114}
                    "book_page" => array:2 [
                      "refs" => "1424367"
                      "type" => "book_page"
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                    "img" => array:1 [
                      0 => array:5 [ …5]
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                  ]
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            "tasks" => Illuminate\Database\Eloquent\Collection {#1168
              #items: array:11 [
                0 => App\Models\Task {#1186
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                  #perPage: 15
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                  #escapeWhenCastingToString: false
                  #attributes: array:24 [
                    "id" => 1424160
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_page_start" => "17"
                    "field_page_end" => null
                    "field_url" => "/9-klass/fizika/artemenkov-zadachnik/3-11"
                    "field_display_title" => "3.11"
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                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1187
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                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1189
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                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1190
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                      #escapeWhenCastingToString: false
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                    "content" => Illuminate\Database\Eloquent\Collection {#1192
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                    "book" => Illuminate\Database\Eloquent\Collection {#1198
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                      #escapeWhenCastingToString: false
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                    "book" => Illuminate\Database\Eloquent\Collection {#1198}
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                    0 => "*"
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                }
                1 => App\Models\Task {#1193
                  #connection: "mysql"
                  #table: "tasks"
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                  #keyType: "int"
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                  #perPage: 15
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                  #escapeWhenCastingToString: false
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                    "created_at" => "2026-04-10 13:58:26"
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                    "content" => Illuminate\Database\Eloquent\Collection {#1195
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                2 => App\Models\Task {#1205
                  #connection: "mysql"
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                    "field_display_title" => "3.13"
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                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1197
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                    "field_metatags_title" => null
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                    "edition_groups" => Illuminate\Database\Eloquent\Collection {#1212
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1208
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1206
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "content" => Illuminate\Database\Eloquent\Collection {#1207
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                      #escapeWhenCastingToString: false
                    }
                    "next" => array:2 [
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                    "previous" => array:2 [
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                      "type" => "task"
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                    "book" => Illuminate\Database\Eloquent\Collection {#1222
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                      #escapeWhenCastingToString: false
                    }
                    "page" => array:2 [
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                    "created_at" => "2026-04-10 13:58:26"
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                    "field_page_end" => null
                    "field_url" => "/9-klass/fizika/artemenkov-zadachnik/3-13"
                    "field_display_title" => "3.13"
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                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1197}
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                    "breadcrumbs" => []
                    "edition_groups" => Illuminate\Database\Eloquent\Collection {#1212}
                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1208}
                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1206}
                    "content" => Illuminate\Database\Eloquent\Collection {#1207}
                    "next" => array:2 [
                      "refs" => "1424163"
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                    "previous" => array:2 [
                      "refs" => "1424161"
                      "type" => "task"
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                    "book" => Illuminate\Database\Eloquent\Collection {#1222}
                    "page" => array:2 [
                      "refs" => "1424367"
                      "type" => "book_page"
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                  #touches: []
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                  #hidden: []
                  #visible: []
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                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
                3 => App\Models\Task {#1217
                  #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" => 1424163
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_page_start" => "17"
                    "field_page_end" => null
                    "field_url" => "/9-klass/fizika/artemenkov-zadachnik/3-14"
                    "field_display_title" => "3.14"
                    "field_outside_task" => null
                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1209
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
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                    "breadcrumbs" => []
                    "edition_groups" => Illuminate\Database\Eloquent\Collection {#1224
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1220
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1218
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "content" => Illuminate\Database\Eloquent\Collection {#1219
                      #items: array:2 [ …2]
                      #escapeWhenCastingToString: false
                    }
                    "next" => array:2 [
                      "refs" => "1424164"
                      "type" => "task"
                    ]
                    "previous" => array:2 [
                      "refs" => "1424162"
                      "type" => "task"
                    ]
                    "book" => Illuminate\Database\Eloquent\Collection {#1234
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "page" => array:2 [
                      "refs" => "1424367"
                      "type" => "book_page"
                    ]
                  ]
                  #original: array:24 [
                    "id" => 1424163
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_page_start" => "17"
                    "field_page_end" => null
                    "field_url" => "/9-klass/fizika/artemenkov-zadachnik/3-14"
                    "field_display_title" => "3.14"
                    "field_outside_task" => null
                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1209}
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
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                    "field_match" => null
                    "breadcrumbs" => []
                    "edition_groups" => Illuminate\Database\Eloquent\Collection {#1224}
                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1220}
                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1218}
                    "content" => Illuminate\Database\Eloquent\Collection {#1219}
                    "next" => array:2 [
                      "refs" => "1424164"
                      "type" => "task"
                    ]
                    "previous" => array:2 [
                      "refs" => "1424162"
                      "type" => "task"
                    ]
                    "book" => Illuminate\Database\Eloquent\Collection {#1234}
                    "page" => array:2 [
                      "refs" => "1424367"
                      "type" => "book_page"
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                  ]
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                  #attributeCastCache: []
                  #dateFormat: null
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                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
                4 => App\Models\Task {#1229
                  #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" => 1424164
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_page_start" => "17"
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                    "field_url" => "/9-klass/fizika/artemenkov-zadachnik/3-15"
                    "field_display_title" => "3.15"
                    "field_outside_task" => null
                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1221
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
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                    "field_match" => null
                    "breadcrumbs" => []
                    "edition_groups" => Illuminate\Database\Eloquent\Collection {#1236
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1232
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1230
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "content" => Illuminate\Database\Eloquent\Collection {#1231
                      #items: array:2 [ …2]
                      #escapeWhenCastingToString: false
                    }
                    "next" => array:2 [
                      "refs" => "1424165"
                      "type" => "task"
                    ]
                    "previous" => array:2 [
                      "refs" => "1424163"
                      "type" => "task"
                    ]
                    "book" => Illuminate\Database\Eloquent\Collection {#1246
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "page" => array:2 [
                      "refs" => "1424367"
                      "type" => "book_page"
                    ]
                  ]
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                    "id" => 1424164
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_page_start" => "17"
                    "field_page_end" => null
                    "field_url" => "/9-klass/fizika/artemenkov-zadachnik/3-15"
                    "field_display_title" => "3.15"
                    "field_outside_task" => null
                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1221}
                    "field_metatags_title" => null
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                    "field_h1" => null
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                    "breadcrumbs" => []
                    "edition_groups" => Illuminate\Database\Eloquent\Collection {#1236}
                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1232}
                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1230}
                    "content" => Illuminate\Database\Eloquent\Collection {#1231}
                    "next" => array:2 [
                      "refs" => "1424165"
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                    ]
                    "previous" => array:2 [
                      "refs" => "1424163"
                      "type" => "task"
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                    "book" => Illuminate\Database\Eloquent\Collection {#1246}
                    "page" => array:2 [
                      "refs" => "1424367"
                      "type" => "book_page"
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                  #changes: []
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                  #attributeCastCache: []
                  #dateFormat: null
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                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
                5 => App\Models\Task {#1241
                  #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" => 1424165
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_page_start" => "17"
                    "field_page_end" => null
                    "field_url" => "/9-klass/fizika/artemenkov-zadachnik/3-16"
                    "field_display_title" => "3.16"
                    "field_outside_task" => null
                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1233
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
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                    "breadcrumbs" => []
                    "edition_groups" => Illuminate\Database\Eloquent\Collection {#1248
                      #items: []
                       …1
                    }
                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1244 …2}
                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1242 …2}
                    "content" => Illuminate\Database\Eloquent\Collection {#1243 …2}
                    "next" => array:2 [ …2]
                    "previous" => array:2 [ …2]
                    "book" => Illuminate\Database\Eloquent\Collection {#1258 …2}
                    "page" => array:2 [ …2]
                  ]
                  #original: array:24 [
                    "id" => 1424165
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_page_start" => "17"
                    "field_page_end" => null
                    "field_url" => "/9-klass/fizika/artemenkov-zadachnik/3-16"
                    "field_display_title" => "3.16"
                    "field_outside_task" => null
                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1233}
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                    "breadcrumbs" => []
                    "edition_groups" => Illuminate\Database\Eloquent\Collection {#1248 …1}
                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1244 …2}
                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1242 …2}
                    "content" => Illuminate\Database\Eloquent\Collection {#1243 …2}
                    "next" => array:2 [ …2]
                    "previous" => array:2 [ …2]
                    "book" => Illuminate\Database\Eloquent\Collection {#1258 …2}
                    "page" => array:2 [ …2]
                  ]
                  #changes: []
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                  #attributeCastCache: []
                  #dateFormat: null
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                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
                6 => App\Models\Task {#1253
                  #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" => 1424166
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_page_start" => "17"
                    "field_page_end" => null
                    "field_url" => "/9-klass/fizika/artemenkov-zadachnik/3-17"
                    "field_display_title" => "3.17"
                    "field_outside_task" => null
                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1245 …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 {#1260 …2}
                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1256 …2}
                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1254 …2}
                    "content" => Illuminate\Database\Eloquent\Collection {#1257 …2}
                    "next" => array:2 [ …2]
                    "previous" => array:2 [ …2]
                    "book" => Illuminate\Database\Eloquent\Collection {#1255 …2}
                    "page" => array:2 [ …2]
                  ]
                  #original: array:24 [
                    "id" => 1424166
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_page_start" => "17"
                    "field_page_end" => null
                    "field_url" => "/9-klass/fizika/artemenkov-zadachnik/3-17"
                    "field_display_title" => "3.17"
                    "field_outside_task" => null
                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1245 …2}
                    "field_metatags_title" => null
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                    "edition_groups" => Illuminate\Database\Eloquent\Collection {#1260 …2}
                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1256 …2}
                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1254 …2}
                    "content" => Illuminate\Database\Eloquent\Collection {#1257 …2}
                    "next" => array:2 [ …2]
                    "previous" => array:2 [ …2]
                    "book" => Illuminate\Database\Eloquent\Collection {#1255 …2}
                    "page" => array:2 [ …2]
                  ]
                  #changes: []
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                  #attributeCastCache: []
                  #dateFormat: null
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                  #dispatchesEvents: []
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                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
                7 => App\Models\Task {#1265
                  #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" => 1424167
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_page_start" => "17"
                    "field_page_end" => null
                    "field_url" => "/9-klass/fizika/artemenkov-zadachnik/3-18"
                    "field_display_title" => "3.18"
                    "field_outside_task" => null
                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1266 …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 {#1267 …2}
                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1268 …2}
                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1269 …2}
                    "content" => Illuminate\Database\Eloquent\Collection {#1271 …2}
                    "next" => array:2 [ …2]
                    "previous" => array:2 [ …2]
                    "book" => Illuminate\Database\Eloquent\Collection {#1277 …2}
                    "page" => array:2 [ …2]
                  ]
                  #original: array:24 [
                    "id" => 1424167
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_page_start" => "17"
                    "field_page_end" => null
                    "field_url" => "/9-klass/fizika/artemenkov-zadachnik/3-18"
                    "field_display_title" => "3.18"
                    "field_outside_task" => null
                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1266 …2}
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
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                    "breadcrumbs" => []
                    "edition_groups" => Illuminate\Database\Eloquent\Collection {#1267 …2}
                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1268 …2}
                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1269 …2}
                    "content" => Illuminate\Database\Eloquent\Collection {#1271 …2}
                    "next" => array:2 [ …2]
                    "previous" => array:2 [ …2]
                    "book" => Illuminate\Database\Eloquent\Collection {#1277 …2}
                    "page" => array:2 [ …2]
                  ]
                  #changes: []
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                  #attributeCastCache: []
                  #dateFormat: null
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                  #dispatchesEvents: []
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                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
                8 => App\Models\Task {#1272
                  #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" => 1424168
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_page_start" => "17"
                    "field_page_end" => null
                    "field_url" => "/9-klass/fizika/artemenkov-zadachnik/3-19"
                    "field_display_title" => "3.19"
                    "field_outside_task" => null
                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1270 …2}
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
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                    "breadcrumbs" => []
                    "edition_groups" => Illuminate\Database\Eloquent\Collection {#1279 …2}
                    "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1275 …2}
                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1273 …2}
                    "content" => Illuminate\Database\Eloquent\Collection {#1274 …2}
                    "next" => array:2 [ …2]
                    "previous" => array:2 [ …2]
                    "book" => Illuminate\Database\Eloquent\Collection {#1289 …2}
                    "page" => array:2 [ …2]
                  ]
                  #original: array:24 [
                    "id" => 1424168
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
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№3.17 (с. 17)
Условие. №3.17 (с. 17)
скриншот условия
Физика, 9 класс Задачник, авторы: Артеменков Денис Александрович, Ломаченков Иван Алексеевич, Панебратцев Юрий Анатольевич, издательство Просвещение, Москва, 2011, страница 17, номер 3.17, Условие

3.17 Велосипедист, движущийся равномерно по прямолинейному участку дороги, увидел, как человек, стоящий у дороги, ударил стержнем по висящему рельсу, а через 2 с услышал звук удара. С какой скоростью двигался велосипедист, если он проехал мимо человека через 2 мин 18 с после начала наблюдения? Скорость звука принять равной 340 м/с.

Решение. №3.17 (с. 17)

Дано:

$t_1 = 2 \text{ с}$

$t_2 = 2 \text{ мин } 18 \text{ с}$

$v_{звука} = 340 \text{ м/с}$

Перевод в систему СИ:

$t_2 = 2 \cdot 60 + 18 = 138 \text{ с}$

Найти:

$v_{вел}$ - скорость велосипедиста.

Решение:

Примем за начало отсчета ($t=0$) момент, когда велосипедист увидел удар. Пусть в этот момент расстояние между ним и человеком, ударившим по рельсу, было равно $S$. Велосипедист движется навстречу источнику звука.

Звук и велосипедист движутся навстречу друг другу. Они встретятся через время $t_1 = 2 \text{ с}$. За это время велосипедист проедет расстояние $S_1 = v_{вел} \cdot t_1$, а звук пройдет расстояние $S_2 = v_{звука} \cdot t_1$. Сумма этих расстояний равна начальному расстоянию $S$:

$S = S_1 + S_2 = v_{вел} \cdot t_1 + v_{звука} \cdot t_1 = (v_{вел} + v_{звука}) \cdot t_1$

С другой стороны, велосипедист преодолел все начальное расстояние $S$ за общее время $t_2$, двигаясь с постоянной скоростью $v_{вел}$. Следовательно, это расстояние также равно:

$S = v_{вел} \cdot t_2$

Поскольку левые части обоих выражений для $S$ равны, мы можем приравнять их правые части:

$(v_{вел} + v_{звука}) \cdot t_1 = v_{вел} \cdot t_2$

Теперь решим это уравнение относительно искомой скорости велосипедиста $v_{вел}$:

$v_{вел} \cdot t_1 + v_{звука} \cdot t_1 = v_{вел} \cdot t_2$

$v_{звука} \cdot t_1 = v_{вел} \cdot t_2 - v_{вел} \cdot t_1$

$v_{звука} \cdot t_1 = v_{вел} \cdot (t_2 - t_1)$

Отсюда выражаем $v_{вел}$:

$v_{вел} = \frac{v_{звука} \cdot t_1}{t_2 - t_1}$

Подставим числовые значения из условия задачи:

$v_{вел} = \frac{340 \text{ м/с} \cdot 2 \text{ с}}{138 \text{ с} - 2 \text{ с}} = \frac{680 \text{ м}}{136 \text{ с}} = 5 \text{ м/с}$

Ответ: скорость велосипедиста равна $5 \text{ м/с}$.

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