زمین
preferred label: Earth @en
type: Concept
related: نوسان آزاد

نوسان
preferred label: oscillation @en
type: Concept
related: نوسان آزاد

نوسان آزاد
alternative label: ارتعاش آزاد
related: نوسان
related: زمین
preferred label: free oscillation @en
type: Concept