Номер 4, страница 188 - 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 5. Статика. Параграф 29. Равновесие тела. Момент силы. Условия равновесия твёрдого тела. Вопросы - номер 4, страница 188.

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                    "field_publication_number" => "2"
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1095 …2}
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1097 …2}
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                    "field_cover_description" => "изображено здание и радуга"
                    "field_publication_year" => "2012"
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                    "field_for_whom" => "Учебник для учащихся общеобразовательных организаций"
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                    "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 {#1098 …2}
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1099 …2}
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1100 …2}
                    "field_url" => "/9-klass/fizika/grachev-uchebnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1101 …2}
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                    "breadcrumbs" => array:3 [ …3]
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                    0 => "*"
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              ]
              #escapeWhenCastingToString: false
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            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1103
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                0 => App\Models\Branch {#1104
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                  #table: "branches"
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                  #keyType: "int"
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                  #attributes: array:24 [
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                    "created_at" => "2026-04-10 13:58:26"
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                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1105 …2}
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                    "book" => Illuminate\Database\Eloquent\Collection {#1107 …2}
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                    "id" => 1437951
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                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1105 …2}
                    "field_page_start" => "181"
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                    "book" => Illuminate\Database\Eloquent\Collection {#1107 …2}
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                  #changes: []
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                    0 => "*"
                  ]
                }
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              #escapeWhenCastingToString: false
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            "updated_at" => null
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            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1068}
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            "book" => Illuminate\Database\Eloquent\Collection {#1070}
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            0 => "*"
          ]
        }
        2 => App\Models\Branch {#1141
          #connection: "mysql"
          #table: "branches"
          #primaryKey: "id"
          #keyType: "int"
          +incrementing: true
          #with: []
          #withCount: []
          +preventsLazyLoading: false
          #perPage: 15
          +exists: true
          +wasRecentlyCreated: false
          #escapeWhenCastingToString: false
          #attributes: array:24 [
            "id" => 1437953
            "created_at" => "2026-04-10 13:58:26"
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            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1142
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              #escapeWhenCastingToString: false
            }
            "field_page_start" => "188"
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            "book" => Illuminate\Database\Eloquent\Collection {#1143
              #items: array:1 [
                0 => App\Models\Book {#1144
                  #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
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                    "field_subject" => Illuminate\Database\Eloquent\Collection {#1145 …2}
                    "field_class" => Illuminate\Database\Eloquent\Collection {#1147 …2}
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1149 …2}
                    "field_author" => Illuminate\Database\Eloquent\Collection {#1151 …2}
                    "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1155 …2}
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1156 …2}
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1158 …2}
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1160 …2}
                    "field_series" => Illuminate\Database\Eloquent\Collection {#1162 …2}
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1164 …2}
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1165 …2}
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1166 …2}
                    "field_publication_number" => "2"
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1168 …2}
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1170 …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"
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                    "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]
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                    "breadcrumbs" => array:3 [ …3]
                  ]
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                    "field_cover" => array:1 [ …1]
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                }
              ]
              #escapeWhenCastingToString: false
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            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1176
              #items: array:1 [
                0 => App\Models\Branch {#1177
                  #connection: "mysql"
                  #table: "branches"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
                  #with: []
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                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1178 …2}
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                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1178 …2}
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                    "book" => Illuminate\Database\Eloquent\Collection {#1180 …2}
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                    0 => "*"
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          ]
        }
      ]
      #escapeWhenCastingToString: false
    }
    "content" => Illuminate\Database\Eloquent\Collection {#1219
      #items: array:2 [
        0 => App\Models\Element {#1220
          #connection: "mysql"
          #table: "elements"
          #primaryKey: "id"
          #keyType: "int"
          +incrementing: true
          #with: []
          #withCount: []
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          #escapeWhenCastingToString: false
          #attributes: array:7 [
            "id" => 1705180
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1221
              #items: array:1 [
                0 => App\Models\Edition {#1222
                  #connection: "mysql"
                  #table: "editions"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
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                  #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 {#1223 …2}
                    "field_content_type" => "free"
                    "field_content_mode" => "text, image"
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                    "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 {#1225 …2}
                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1226 …2}
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                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1227 …2}
                    "field_content_source" => null
                  ]
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                    "created_at" => "2026-04-10 13:58:26"
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                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1223 …2}
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                    "field_solution_author" => "Автор"
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                    "field_root_dir" => "0-"
                    "field_responsible" => Illuminate\Database\Eloquent\Collection {#1225 …2}
                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1226 …2}
                    "field_process_formula" => "katex"
                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1227 …2}
                    "field_content_source" => null
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
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                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
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                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "task" => array:2 [
              "refs" => "1438289"
              "type" => "task"
            ]
            "text" => "<p><strong>4.</strong> Сформулируйте условия равновесия твёрдого тела.</p>"
            "img" => array:1 [
              0 => array:5 [
                "name" => "4-1.jpg"
                "alt" => null
                "width" => "392"
                "height" => 70
                "path" => "/media/fizika_09/grachev-u/0-29vopr/4-1.webp?ts=1759503156"
              ]
            ]
          ]
          #original: array:7 [
            "id" => 1705180
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1221}
            "task" => array:2 [
              "refs" => "1438289"
              "type" => "task"
            ]
            "text" => "<p><strong>4.</strong> Сформулируйте условия равновесия твёрдого тела.</p>"
            "img" => array:1 [
              0 => array:5 [
                "name" => "4-1.jpg"
                "alt" => null
                "width" => "392"
                "height" => 70
                "path" => "/media/fizika_09/grachev-u/0-29vopr/4-1.webp?ts=1759503156"
              ]
            ]
          ]
          #changes: []
          #casts: []
          #classCastCache: []
          #attributeCastCache: []
          #dateFormat: null
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          +timestamps: true
          +usesUniqueIds: false
          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
        1 => App\Models\Element {#1228
          #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" => 1812864
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1229
              #items: array:1 [
                0 => App\Models\Edition {#1230
                  #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 {#1231 …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 {#1233 …2}
                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1234 …2}
                    "field_process_formula" => "katex"
                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1235 …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 {#1231 …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 {#1233 …2}
                    "field_comment" => null
                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1234 …2}
                    "field_process_formula" => "katex"
                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1235 …2}
                    "field_content_source" => null
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
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                  #observables: []
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                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "task" => array:2 [
              "refs" => "1438289"
              "type" => "task"
            ]
            "text" => "<p>Для того чтобы абсолютно твёрдое тело находилось в состоянии равновесия в инерциальной системе отсчёта, необходимо и достаточно, чтобы одновременно выполнялись два условия.</p><p><strong>Первое условие равновесия (условие равновесия для поступательного движения)</strong>. Это условие гласит, что векторная сумма всех внешних сил, действующих на тело, должна быть равна нулю. Если это условие выполнено, то центр масс тела либо покоится, либо движется прямолинейно и равномерно, то есть ускорение центра масс равно нулю. Математически это записывается как:</p><p>$\sum \vec{F} = \vec{F}_1 + \vec{F}_2 + ... + \vec{F}_n = \vec{0}$</p><p>В проекциях на оси декартовой системы координат это условие выглядит так:</p><p>$\sum F_x = 0; \quad \sum F_y = 0; \quad \sum F_z = 0$</p><p>Выполнение этого условия обеспечивает отсутствие ускоренного поступательного движения.</p><p><strong>Второе условие равновесия (условие равновесия для вращательного движения)</strong>. Это условие, также известное как правило моментов, гласит, что сумма моментов всех внешних сил относительно любой произвольно выбранной оси (или точки) должна быть равна нулю. Если это условие выполнено, тело не вращается или вращается с постоянной угловой скоростью, то есть его угловое ускорение равно нулю. Математически это записывается как:</p><p>$\sum \vec{M} = \vec{M}_1 + \vec{M}_2 + ... + \vec{M}_n = \vec{0}$</p><p>Для случая, когда все силы лежат в одной плоскости, это условие можно записать в скалярной форме. Сумма моментов сил, вращающих тело по часовой стрелке, должна быть равна сумме моментов сил, вращающих его против часовой стрелки. Алгебраически:</p><p>$\sum M = 0$</p><p>Выполнение этого условия обеспечивает отсутствие ускоренного вращательного движения.</p><p><strong>Ответ:</strong> Для равновесия твёрдого тела необходимо, чтобы выполнялись два условия: 1) векторная сумма всех внешних сил, приложенных к телу, равна нулю; 2) сумма моментов всех внешних сил относительно любой оси равна нулю.</p>"
          ]
          #original: array:6 [
            "id" => 1812864
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1229}
            "task" => array:2 [
              "refs" => "1438289"
              "type" => "task"
            ]
            "text" => "<p>Для того чтобы абсолютно твёрдое тело находилось в состоянии равновесия в инерциальной системе отсчёта, необходимо и достаточно, чтобы одновременно выполнялись два условия.</p><p><strong>Первое условие равновесия (условие равновесия для поступательного движения)</strong>. Это условие гласит, что векторная сумма всех внешних сил, действующих на тело, должна быть равна нулю. Если это условие выполнено, то центр масс тела либо покоится, либо движется прямолинейно и равномерно, то есть ускорение центра масс равно нулю. Математически это записывается как:</p><p>$\sum \vec{F} = \vec{F}_1 + \vec{F}_2 + ... + \vec{F}_n = \vec{0}$</p><p>В проекциях на оси декартовой системы координат это условие выглядит так:</p><p>$\sum F_x = 0; \quad \sum F_y = 0; \quad \sum F_z = 0$</p><p>Выполнение этого условия обеспечивает отсутствие ускоренного поступательного движения.</p><p><strong>Второе условие равновесия (условие равновесия для вращательного движения)</strong>. Это условие, также известное как правило моментов, гласит, что сумма моментов всех внешних сил относительно любой произвольно выбранной оси (или точки) должна быть равна нулю. Если это условие выполнено, тело не вращается или вращается с постоянной угловой скоростью, то есть его угловое ускорение равно нулю. Математически это записывается как:</p><p>$\sum \vec{M} = \vec{M}_1 + \vec{M}_2 + ... + \vec{M}_n = \vec{0}$</p><p>Для случая, когда все силы лежат в одной плоскости, это условие можно записать в скалярной форме. Сумма моментов сил, вращающих тело по часовой стрелке, должна быть равна сумме моментов сил, вращающих его против часовой стрелки. Алгебраически:</p><p>$\sum M = 0$</p><p>Выполнение этого условия обеспечивает отсутствие ускоренного вращательного движения.</p><p><strong>Ответ:</strong> Для равновесия твёрдого тела необходимо, чтобы выполнялись два условия: 1) векторная сумма всех внешних сил, приложенных к телу, равна нулю; 2) сумма моментов всех внешних сил относительно любой оси равна нулю.</p>"
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      "type" => "task"
    ]
    "book" => Illuminate\Database\Eloquent\Collection {#1236
      #items: array:1 [
        0 => App\Models\Book {#1237
          #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 {#1238
              #items: array:1 [
                0 => App\Models\Term {#1239
                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
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                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #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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                  #original: 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
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                    "field_subject_type" => "technical_subject"
                    "field_translit" => "fizika"
                  ]
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                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_class" => Illuminate\Database\Eloquent\Collection {#1240
              #items: array:1 [
                0 => App\Models\Term {#1241
                  #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"
                  ]
                  #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"
                  ]
                  #changes: []
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                  +timestamps: true
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                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_publisher" => Illuminate\Database\Eloquent\Collection {#1242
              #items: array:1 [
                0 => App\Models\Term {#1243
                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
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                  #perPage: 15
                  +exists: true
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                  #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"
                  ]
                  #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 {#1244
              #items: array:3 [
                0 => App\Models\Term {#1245
                  #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" => 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
                  ]
                  #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
                  ]
                  #changes: []
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                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
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                  +timestamps: true
                  +usesUniqueIds: false
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                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
                1 => App\Models\Term {#1246
                  #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
                    "field_foreign_lang_name" => null
                    "field_foreign_lang_patronymic" => null
                    "field_foreign_lang_surname" => null
                    "field_name" => "Владимир"
                    "field_patronymic" => "Александрович"
                    "field_surname_rp" => null
                  ]
                  #original: array:12 [
                    "id" => 5484
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Погожев"
                    "field_bio" => null
                    "field_degree_rp" => null
                    "field_foreign_lang_name" => null
                    "field_foreign_lang_patronymic" => null
                    "field_foreign_lang_surname" => null
                    "field_name" => "Владимир"
                    "field_patronymic" => "Александрович"
                    "field_surname_rp" => null
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
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                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
                2 => App\Models\Term {#1247
                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array: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"
                    "field_patronymic" => "Юрьевич"
                    "field_surname_rp" => null
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1248
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_book_type" => Illuminate\Database\Eloquent\Collection {#1249
              #items: array:1 [
                0 => App\Models\Term {#1250
                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:10 [
                    "id" => 6671
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Учебник"
                    "field_book_type_foreign" => null
                    "field_cases" => array:6 [ …6]
                    "field_plural_form" => null
                    "field_short_name" => null
                    "field_short_name_foreign" => null
                    "field_translit" => "uchebnik"
                  ]
                  #original: array:10 [
                    "id" => 6671
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Учебник"
                    "field_book_type_foreign" => null
                    "field_cases" => array:6 [ …6]
                    "field_plural_form" => null
                    "field_short_name" => null
                    "field_short_name_foreign" => null
                    "field_translit" => "uchebnik"
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_country" => Illuminate\Database\Eloquent\Collection {#1251
              #items: array:1 [
                0 => App\Models\Term {#1252
                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:6 [
                    "id" => 9
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Россия"
                     …2
                  ]
                  #original: array:6 [ …6]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [ …1]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_city" => Illuminate\Database\Eloquent\Collection {#1253
              #items: array:1 [
                0 => App\Models\Term {#1254
                  #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 [ …6]
                  #original: array:6 [ …6]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [ …1]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_series" => Illuminate\Database\Eloquent\Collection {#1255
              #items: array:1 [
                0 => App\Models\Term {#1256
                  #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 [ …8]
                  #original: array:8 [ …8]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [ …1]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_umk" => Illuminate\Database\Eloquent\Collection {#1257
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1258
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1259
              #items: array:1 [
                0 => App\Models\Term {#1260
                  #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 [ …10]
                  #original: array:10 [ …10]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [ …1]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_publication_number" => "2"
            "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1261
              #items: array:1 [
                0 => App\Models\Term {#1262
                  #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 [ …6]
                  #original: array:6 [ …6]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [ …1]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1263
              #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 {#1264
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_new_book" => Illuminate\Database\Eloquent\Collection {#1265
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_old_book" => Illuminate\Database\Eloquent\Collection {#1266
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_url" => "/9-klass/fizika/grachev-uchebnik"
            "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1267
              #items: array:1 [
                0 => App\Models\Term {#1268
                  #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 [ …6]
                  #original: array:6 [ …6]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [ …1]
                }
              ]
              #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 {#1238}
            "field_class" => Illuminate\Database\Eloquent\Collection {#1240}
            "field_publisher" => Illuminate\Database\Eloquent\Collection {#1242}
            "field_author" => Illuminate\Database\Eloquent\Collection {#1244}
            "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1248}
            "field_book_type" => Illuminate\Database\Eloquent\Collection {#1249}
            "field_country" => Illuminate\Database\Eloquent\Collection {#1251}
            "field_city" => Illuminate\Database\Eloquent\Collection {#1253}
            "field_series" => Illuminate\Database\Eloquent\Collection {#1255}
            "field_umk" => Illuminate\Database\Eloquent\Collection {#1257}
            "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1258}
            "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1259}
            "field_publication_number" => "2"
            "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1261}
            "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1263}
            "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 {#1264}
            "field_new_book" => Illuminate\Database\Eloquent\Collection {#1265}
            "field_old_book" => Illuminate\Database\Eloquent\Collection {#1266}
            "field_url" => "/9-klass/fizika/grachev-uchebnik"
            "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1267}
            "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: []
          #casts: []
          #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 {#1898
      #items: array:1 [
        0 => App\Models\BookPage {#1272
          #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" => 1437694
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_page_start" => "188"
            "field_url" => "/9-klass/fizika/grachev-uchebnik/page-188"
            "field_display_title" => "188"
            "field_folder" => "1"
            "field_image_name" => "188"
            "field_branch_parent" => Illuminate\Database\Eloquent\Collection {#1276
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_weight" => "0"
            "field_book_parent" => Illuminate\Database\Eloquent\Collection {#1275
              #items: array:1 [
                0 => App\Models\Book {#1277
                  #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 [ …50]
                  #original: array:50 [ …50]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [ …1]
                }
              ]
              #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 {#1309
              #items: []
              #escapeWhenCastingToString: false
            }
            "content" => Illuminate\Database\Eloquent\Collection {#1310
              #items: array:1 [
                0 => App\Models\Element {#1311
                  #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 [ …6]
                  #original: array:6 [ …6]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [ …1]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "next" => array:2 [
              "refs" => "1437695"
              "type" => "book_page"
            ]
            "previous" => array:2 [
              "refs" => "1437693"
              "type" => "book_page"
            ]
            "tasks" => Illuminate\Database\Eloquent\Collection {#1319
              #items: array:10 [
                0 => App\Models\Task {#1320
                  #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 [ …24]
                  #original: array:24 [ …24]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [ …1]
                }
                1 => App\Models\Task {#1564
                  #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 [ …24]
                  #original: array:24 [ …24]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [ …1]
                }
                2 => App\Models\Task {#1575
                  #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 [ …24]
                  #original: array:24 [ …24]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [ …1]
                }
                3 => App\Models\Task {#1586
                  #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 [ …24]
                  #original: array:24 [ …24]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [ …1]
                }
                4 => App\Models\Task {#1597
                  #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 [ …24]
                  #original: array:24 [ …24]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [ …1]
                }
                5 => App\Models\Task {#1608
                  #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 [ …24]
                  #original: array:24 [ …24]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
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№4 (с. 188)
Условие. №4 (с. 188)
скриншот условия
Физика, 9 класс Учебник, авторы: Грачев Александр Васильевич, Погожев Владимир Александрович, Боков Павел Юрьевич, издательство Вентана-граф, Москва, 2012, страница 188, номер 4, Условие

4. Сформулируйте условия равновесия твёрдого тела.

Решение. №4 (с. 188)

Для того чтобы абсолютно твёрдое тело находилось в состоянии равновесия в инерциальной системе отсчёта, необходимо и достаточно, чтобы одновременно выполнялись два условия.

Первое условие равновесия (условие равновесия для поступательного движения). Это условие гласит, что векторная сумма всех внешних сил, действующих на тело, должна быть равна нулю. Если это условие выполнено, то центр масс тела либо покоится, либо движется прямолинейно и равномерно, то есть ускорение центра масс равно нулю. Математически это записывается как:

$\sum \vec{F} = \vec{F}_1 + \vec{F}_2 + ... + \vec{F}_n = \vec{0}$

В проекциях на оси декартовой системы координат это условие выглядит так:

$\sum F_x = 0; \quad \sum F_y = 0; \quad \sum F_z = 0$

Выполнение этого условия обеспечивает отсутствие ускоренного поступательного движения.

Второе условие равновесия (условие равновесия для вращательного движения). Это условие, также известное как правило моментов, гласит, что сумма моментов всех внешних сил относительно любой произвольно выбранной оси (или точки) должна быть равна нулю. Если это условие выполнено, тело не вращается или вращается с постоянной угловой скоростью, то есть его угловое ускорение равно нулю. Математически это записывается как:

$\sum \vec{M} = \vec{M}_1 + \vec{M}_2 + ... + \vec{M}_n = \vec{0}$

Для случая, когда все силы лежат в одной плоскости, это условие можно записать в скалярной форме. Сумма моментов сил, вращающих тело по часовой стрелке, должна быть равна сумме моментов сил, вращающих его против часовой стрелки. Алгебраически:

$\sum M = 0$

Выполнение этого условия обеспечивает отсутствие ускоренного вращательного движения.

Ответ: Для равновесия твёрдого тела необходимо, чтобы выполнялись два условия: 1) векторная сумма всех внешних сил, приложенных к телу, равна нулю; 2) сумма моментов всех внешних сил относительно любой оси равна нулю.

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