question_answer

Two simple pendulums of length 1m and 4mrespectively are both given small d is placement in the same direction at the same instant. They will be again in phase after the shorter pendulum has completed number of oscillations equal to: [JEE ONLINE 09-04-2013]

A)        2        

B)       7

C)  5                    

D)       3

Correct Answer: A

Solution :

[a] Let  and  be the time period of shorter length and larger length pendulums respectively. According to question,

So,

or