Two simple pendulum of length `5m` and `20m` respectively are given small displacement in time direction at the same time. They will again in the plane when the pendulum of shorter length has completed oscillation.

Options

A. 5
B. 1
C. 2
D. 3

Answer

C

Explanation

Since, `Tprop sqrt(l)`
`implies (T_(1))/(T_(2))=sqrt((l_(1))/(l_(2)))`
`implies (f_(2))/(f_(1))=sqrt((l_(1))/(l_(2)))implies (f_(2))/(f_(1))=sqrt((5)/(20))`
`implies (f_(2))/(f_(1))=(1)/(2) implies f_(1)=2f_(2)`
as `f_(2)=1," "f_(1)=2`.