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

Options

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

Answer

C

Explanation

`(n_(2))/(n_(1))=sqrt((l_(1))/(l_(2)))=sqrt((5)/(20))=(1)/(sqrt(4))=(1)/(2)`
`therefore(n_(1))/(n_(2))=2" "therefore(n_(1)-n_(2))/(n_(2))=2-1=1`
`n_(1)-n_(2)=1`
`(1)/(n_(2))=1" "n_(2)=1`
`n_(1)=n_(2)+1=1+2=2`