Two pendulum of different lengths are in phase at the mean position at a certain instant . The minimum time after which they will

Question

Be again in phase is 5T/4 ,where T is the time period of smaller pendulum . Find the ratio of lengths of two pendulums

Answer 1

hey,

When the pendulum A with time period 45T​ completes phase of 2π in 45T​, the other pendulum B leads by phase 2π​.
So after 4 oscillations of pendulum A i.e. after 5T, pendulum B leads by 2π i.e they come in phase.
i.e. after 5 oscillations of small pendulum ( Time taken=5T), they will again come in the same phase.