Задачи по физике по теме: "Механические волны"

object(ArrayObject)#851 (1) {
  ["storage":"ArrayObject":private] => array(6) {
    ["title"] => string(64) ""Механические волны"-физика 9 класс "
    ["seo_title"] => string(38) "miekhanichieskiie-volny-fizika-9-klass"
    ["file_id"] => string(6) "176898"
    ["category_seo"] => string(6) "fizika"
    ["subcategory_seo"] => string(5) "uroki"
    ["date"] => string(10) "1424514856"
  }
}

object(ArrayObject)#873 (1) {
  ["storage":"ArrayObject":private] => array(6) {
    ["title"] => string(104) "Механические волны. Свойства механических волн  (статья) "
    ["seo_title"] => string(63) "miekhanichieskiie-volny-svoistva-miekhanichieskikh-voln-stat-ia"
    ["file_id"] => string(6) "121378"
    ["category_seo"] => string(6) "fizika"
    ["subcategory_seo"] => string(7) "prochee"
    ["date"] => string(10) "1413961062"
  }
}

object(ArrayObject)#851 (1) {
  ["storage":"ArrayObject":private] => array(6) {
    ["title"] => string(52) "ИНТЕГРАЦИЯ НА УРОКАХ ФИЗИКИ "
    ["seo_title"] => string(31) "intiegratsiia-na-urokakh-fiziki"
    ["file_id"] => string(6) "101590"
    ["category_seo"] => string(6) "fizika"
    ["subcategory_seo"] => string(7) "prochee"
    ["date"] => string(10) "1402422855"
  }
}

object(ArrayObject)#873 (1) {
  ["storage":"ArrayObject":private] => array(6) {
    ["title"] => string(84) "Конспект урока физики по теме "Звуковые волны""
    ["seo_title"] => string(48) "konspiekt-uroka-fiziki-po-tiemie-zvukovyie-volny"
    ["file_id"] => string(6) "263939"
    ["category_seo"] => string(6) "fizika"
    ["subcategory_seo"] => string(5) "uroki"
    ["date"] => string(10) "1449614223"
  }
}

object(ArrayObject)#851 (1) {
  ["storage":"ArrayObject":private] => array(6) {
    ["title"] => string(92) "Конспект урока физики по теме "Механические волны""
    ["seo_title"] => string(56) "konspiekt-uroka-fiziki-po-tiemie-miekhanichieskiie-volny"
    ["file_id"] => string(6) "303698"
    ["category_seo"] => string(6) "fizika"
    ["subcategory_seo"] => string(5) "uroki"
    ["date"] => string(10) "1457590159"
  }
}