Номер 8, страница 335 - 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 9. Физика атома и атомного ядра. Параграф 57. Ядерные реакции. Деление и синтез ядер. Ядерная энергетика. Источники энергии Солнца и звёзд. Вопросы - номер 8, страница 335.

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                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1101 …2}
                    "field_publication_number" => "2"
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1103 …2}
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1105 …2}
                    "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 [ …1]
                    "field_cover_alts" => array:1 [ …1]
                    "field_covers" => array:1 [ …1]
                    "field_popular_book" => "0"
                    "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1106 …2}
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1107 …2}
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1108 …2}
                    "field_url" => "/9-klass/fizika/grachev-uchebnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1109 …2}
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "breadcrumbs" => array:3 [ …3]
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1111
              #items: []
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1438011
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Физика атома и атомного ядра"
            "field_branch_order" => "9"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1077}
            "field_page_start" => "307"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
            "field_display_task_interval" => "0"
            "field_display_branch_page" => "1"
            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1078}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1111}
          ]
          #changes: []
          #casts: []
          #classCastCache: []
          #attributeCastCache: []
          #dateFormat: null
          #appends: []
          #dispatchesEvents: []
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          #relations: []
          #touches: []
          +timestamps: true
          +usesUniqueIds: false
          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
        1 => App\Models\Branch {#1112
          #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" => 1438027
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Ядерные реакции. Деление и синтез ядер. Ядерная энергетика. Источники энергии Солнца и звёзд"
            "field_branch_order" => "57"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1113
              #items: array:1 [
                0 => App\Models\Term {#1114
                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:7 [
                    "id" => 32
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Параграф"
                    "field_cases" => array:6 [ …6]
                    "field_page_check_not_needed" => null
                    "field_short_name" => "§"
                  ]
                  #original: array:7 [
                    "id" => 32
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Параграф"
                    "field_cases" => array:6 [ …6]
                    "field_page_check_not_needed" => null
                    "field_short_name" => "§"
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "330"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
            "field_display_task_interval" => "0"
            "field_display_branch_page" => "1"
            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1115
              #items: array:1 [
                0 => App\Models\Book {#1116
                  #connection: "mysql"
                  #table: "books"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +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 {#1117 …2}
                    "field_class" => Illuminate\Database\Eloquent\Collection {#1119 …2}
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1121 …2}
                    "field_author" => Illuminate\Database\Eloquent\Collection {#1123 …2}
                    "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1127 …2}
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1128 …2}
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1130 …2}
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1132 …2}
                    "field_series" => Illuminate\Database\Eloquent\Collection {#1134 …2}
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1136 …2}
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1137 …2}
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1138 …2}
                    "field_publication_number" => "2"
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1140 …2}
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1142 …2}
                    "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
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                    "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 [ …1]
                    "field_cover_alts" => array:1 [ …1]
                    "field_covers" => array:1 [ …1]
                    "field_popular_book" => "0"
                    "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1143 …2}
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1144 …2}
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1145 …2}
                    "field_url" => "/9-klass/fizika/grachev-uchebnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1146 …2}
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
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                    "breadcrumbs" => array:3 [ …3]
                  ]
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                    "created_at" => "2026-04-10 13:58:26"
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                    "field_tree_default_status" => "tasks"
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                    "field_subject" => Illuminate\Database\Eloquent\Collection {#1117 …2}
                    "field_class" => Illuminate\Database\Eloquent\Collection {#1119 …2}
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1121 …2}
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                    "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1127 …2}
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1128 …2}
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1130 …2}
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1132 …2}
                    "field_series" => Illuminate\Database\Eloquent\Collection {#1134 …2}
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1136 …2}
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1137 …2}
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1138 …2}
                    "field_publication_number" => "2"
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1140 …2}
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1142 …2}
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                    "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 [ …1]
                    "field_cover_alts" => array:1 [ …1]
                    "field_covers" => array:1 [ …1]
                    "field_popular_book" => "0"
                    "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1143 …2}
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1144 …2}
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1145 …2}
                    "field_url" => "/9-klass/fizika/grachev-uchebnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1146 …2}
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "breadcrumbs" => array:3 [ …3]
                  ]
                  #changes: []
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                  #attributeCastCache: []
                  #dateFormat: null
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                  #touches: []
                  +timestamps: true
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                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1148
              #items: array:1 [
                0 => App\Models\Branch {#1149
                  #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" => 1438011
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Физика атома и атомного ядра"
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                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1150 …2}
                    "field_page_start" => "307"
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                    "field_display_branch_page" => "1"
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                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "field_branch_cover" => []
                    "field_branch_covers" => []
                    "book" => Illuminate\Database\Eloquent\Collection {#1152 …2}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1185 …2}
                  ]
                  #original: array:24 [
                    "id" => 1438011
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Физика атома и атомного ядра"
                    "field_branch_order" => "9"
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1150 …2}
                    "field_page_start" => "307"
                    "field_branch_display" => "0"
                    "field_branch_expanded" => "0"
                    "field_display_branch_in_title" => "1"
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                    "field_display_branch_page" => "1"
                    "field_branch_title_in_content" => "0"
                    "field_navigation_title" => null
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "field_branch_cover" => []
                    "field_branch_covers" => []
                    "book" => Illuminate\Database\Eloquent\Collection {#1152 …2}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1185 …2}
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1438027
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Ядерные реакции. Деление и синтез ядер. Ядерная энергетика. Источники энергии Солнца и звёзд"
            "field_branch_order" => "57"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1113}
            "field_page_start" => "330"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
            "field_display_task_interval" => "0"
            "field_display_branch_page" => "1"
            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1115}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1148}
          ]
          #changes: []
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          #classCastCache: []
          #attributeCastCache: []
          #dateFormat: null
          #appends: []
          #dispatchesEvents: []
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          #relations: []
          #touches: []
          +timestamps: true
          +usesUniqueIds: false
          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
        2 => App\Models\Branch {#1186
          #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" => 1438028
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Вопросы"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1187
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "335"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
            "field_display_task_interval" => "0"
            "field_display_branch_page" => "1"
            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1188
              #items: array:1 [
                0 => App\Models\Book {#1189
                  #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 {#1190 …2}
                    "field_class" => Illuminate\Database\Eloquent\Collection {#1192 …2}
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1194 …2}
                    "field_author" => Illuminate\Database\Eloquent\Collection {#1196 …2}
                    "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1200 …2}
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1201 …2}
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1203 …2}
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1205 …2}
                    "field_series" => Illuminate\Database\Eloquent\Collection {#1207 …2}
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1209 …2}
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1210 …2}
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1211 …2}
                    "field_publication_number" => "2"
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1213 …2}
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1215 …2}
                    "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 [ …1]
                    "field_cover_alts" => array:1 [ …1]
                    "field_covers" => array:1 [ …1]
                    "field_popular_book" => "0"
                    "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1216 …2}
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            "text" => "<p><strong>Что такое замедлители и какова их роль?</strong></p><p>Замедлители нейтронов — это вещества, которые используются в ядерных реакторах для уменьшения кинетической энергии быстрых нейтронов до тепловых энергий. Быстрые нейтроны образуются в результате реакции ядерного деления. В качестве замедлителей, как правило, применяют вещества, состоящие из лёгких элементов, которые эффективно замедляют нейтроны, но слабо их поглощают.</p><p>Роль замедлителей является ключевой для поддержания управляемой цепной реакции деления в большинстве типов реакторов, особенно тех, что работают на природном или низкообогащённом уране. Механизм их действия следующий:</p><ol><li>При делении тяжёлых ядер, например, урана-235 (${}_{92}^{235}U$), испускаются 2–3 нейтрона. Эти нейтроны обладают высокой кинетической энергией (в среднем около 2 МэВ) и называются быстрыми нейтронами.</li><li>Вероятность того, что такой быстрый нейтрон вызовет деление следующего ядра ${}_{92}^{235}U$, относительно невелика. Реакция деления урана-235 наиболее эффективно идёт под действием медленных (тепловых) нейтронов.</li><li>Задача замедлителя — снизить энергию быстрых нейтронов до теплового уровня (около 0,025 эВ). Это происходит в результате многократных упругих столкновений нейтронов с ядрами атомов замедлителя.</li><li>Согласно законам механики, передача энергии при упругом столкновении наиболее эффективна, когда массы сталкивающихся частиц близки. Поскольку масса нейтрона очень мала, для его замедления требуются вещества с лёгкими ядрами (например, водорода, дейтерия, углерода).</li><li>Замедлившись до тепловых энергий, нейтроны с гораздо большей вероятностью (в сотни раз выше, чем у быстрых нейтронов) захватываются ядрами ${}_{92}^{235}U$ и вызывают их деление. Это позволяет поддерживать непрерывную цепную реакцию.</li></ol><p>Таким образом, замедлитель создаёт условия для эффективного протекания цепной реакции, делая возможной работу ядерного реактора.</p><p>Наиболее распространённые вещества-замедлители:</p><ul><li>Обычная (лёгкая) вода ($H_2O$)</li><li>Тяжёлая вода ($D_2O$)</li><li>Графит ($\text{C}$)</li><li>Бериллий ($Be$)</li></ul><p><strong>Ответ:</strong> Замедлители — это вещества в ядерных реакторах (например, вода, графит), состоящие из лёгких элементов. Их роль заключается в том, чтобы замедлять быстрые нейтроны, образующиеся при делении ядер, до тепловых энергий. Это критически важно, поскольку тепловые нейтроны с гораздо большей вероятностью вызывают последующие деления ядер урана-235, что необходимо для поддержания управляемой цепной реакции.</p>"
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            "text" => "<p><strong>Что такое замедлители и какова их роль?</strong></p><p>Замедлители нейтронов — это вещества, которые используются в ядерных реакторах для уменьшения кинетической энергии быстрых нейтронов до тепловых энергий. Быстрые нейтроны образуются в результате реакции ядерного деления. В качестве замедлителей, как правило, применяют вещества, состоящие из лёгких элементов, которые эффективно замедляют нейтроны, но слабо их поглощают.</p><p>Роль замедлителей является ключевой для поддержания управляемой цепной реакции деления в большинстве типов реакторов, особенно тех, что работают на природном или низкообогащённом уране. Механизм их действия следующий:</p><ol><li>При делении тяжёлых ядер, например, урана-235 (${}_{92}^{235}U$), испускаются 2–3 нейтрона. Эти нейтроны обладают высокой кинетической энергией (в среднем около 2 МэВ) и называются быстрыми нейтронами.</li><li>Вероятность того, что такой быстрый нейтрон вызовет деление следующего ядра ${}_{92}^{235}U$, относительно невелика. Реакция деления урана-235 наиболее эффективно идёт под действием медленных (тепловых) нейтронов.</li><li>Задача замедлителя — снизить энергию быстрых нейтронов до теплового уровня (около 0,025 эВ). Это происходит в результате многократных упругих столкновений нейтронов с ядрами атомов замедлителя.</li><li>Согласно законам механики, передача энергии при упругом столкновении наиболее эффективна, когда массы сталкивающихся частиц близки. Поскольку масса нейтрона очень мала, для его замедления требуются вещества с лёгкими ядрами (например, водорода, дейтерия, углерода).</li><li>Замедлившись до тепловых энергий, нейтроны с гораздо большей вероятностью (в сотни раз выше, чем у быстрых нейтронов) захватываются ядрами ${}_{92}^{235}U$ и вызывают их деление. Это позволяет поддерживать непрерывную цепную реакцию.</li></ol><p>Таким образом, замедлитель создаёт условия для эффективного протекания цепной реакции, делая возможной работу ядерного реактора.</p><p>Наиболее распространённые вещества-замедлители:</p><ul><li>Обычная (лёгкая) вода ($H_2O$)</li><li>Тяжёлая вода ($D_2O$)</li><li>Графит ($\text{C}$)</li><li>Бериллий ($Be$)</li></ul><p><strong>Ответ:</strong> Замедлители — это вещества в ядерных реакторах (например, вода, графит), состоящие из лёгких элементов. Их роль заключается в том, чтобы замедлять быстрые нейтроны, образующиеся при делении ядер, до тепловых энергий. Это критически важно, поскольку тепловые нейтроны с гораздо большей вероятностью вызывают последующие деления ядер урана-235, что необходимо для поддержания управляемой цепной реакции.</p>"
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№8 (с. 335)
Условие. №8 (с. 335)
скриншот условия
Физика, 9 класс Учебник, авторы: Грачев Александр Васильевич, Погожев Владимир Александрович, Боков Павел Юрьевич, издательство Вентана-граф, Москва, 2012, страница 335, номер 8, Условие

8. Что такое замедлители и какова их роль?

Решение. №8 (с. 335)

Что такое замедлители и какова их роль?

Замедлители нейтронов — это вещества, которые используются в ядерных реакторах для уменьшения кинетической энергии быстрых нейтронов до тепловых энергий. Быстрые нейтроны образуются в результате реакции ядерного деления. В качестве замедлителей, как правило, применяют вещества, состоящие из лёгких элементов, которые эффективно замедляют нейтроны, но слабо их поглощают.

Роль замедлителей является ключевой для поддержания управляемой цепной реакции деления в большинстве типов реакторов, особенно тех, что работают на природном или низкообогащённом уране. Механизм их действия следующий:

  1. При делении тяжёлых ядер, например, урана-235 (${}_{92}^{235}U$), испускаются 2–3 нейтрона. Эти нейтроны обладают высокой кинетической энергией (в среднем около 2 МэВ) и называются быстрыми нейтронами.
  2. Вероятность того, что такой быстрый нейтрон вызовет деление следующего ядра ${}_{92}^{235}U$, относительно невелика. Реакция деления урана-235 наиболее эффективно идёт под действием медленных (тепловых) нейтронов.
  3. Задача замедлителя — снизить энергию быстрых нейтронов до теплового уровня (около 0,025 эВ). Это происходит в результате многократных упругих столкновений нейтронов с ядрами атомов замедлителя.
  4. Согласно законам механики, передача энергии при упругом столкновении наиболее эффективна, когда массы сталкивающихся частиц близки. Поскольку масса нейтрона очень мала, для его замедления требуются вещества с лёгкими ядрами (например, водорода, дейтерия, углерода).
  5. Замедлившись до тепловых энергий, нейтроны с гораздо большей вероятностью (в сотни раз выше, чем у быстрых нейтронов) захватываются ядрами ${}_{92}^{235}U$ и вызывают их деление. Это позволяет поддерживать непрерывную цепную реакцию.

Таким образом, замедлитель создаёт условия для эффективного протекания цепной реакции, делая возможной работу ядерного реактора.

Наиболее распространённые вещества-замедлители:

  • Обычная (лёгкая) вода ($H_2O$)
  • Тяжёлая вода ($D_2O$)
  • Графит ($\text{C}$)
  • Бериллий ($Be$)

Ответ: Замедлители — это вещества в ядерных реакторах (например, вода, графит), состоящие из лёгких элементов. Их роль заключается в том, чтобы замедлять быстрые нейтроны, образующиеся при делении ядер, до тепловых энергий. Это критически важно, поскольку тепловые нейтроны с гораздо большей вероятностью вызывают последующие деления ядер урана-235, что необходимо для поддержания управляемой цепной реакции.

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