Two simple pendulums of lengths 100 cm and 144cm start oscillating together at time t = 0. The minimum time after which they swing together is (take `g=pi^(2)ms^(-2)`)

Options

A. 2 s
B. 4 s
C. 10 s
D. 12 s

Answer

D

Explanation

100 cm pendulum is a second's pendulum,
`T=2s`
`Nsqrt(l)` = constant
N = Number of oscillations in a given time `Nxxsqrt(100)=(N-1)sqrt(144)`
`10N=12N-12`
`2N=12,N=6`
`therefore t=6xx2`
`=12s`