Two pendulums have time periods T and 5T/4. They start SHM at the same time from the mean position. After how many oscillations of the smaller pendulum they will be again in the same phase:
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Question

Two pendulums have time periods T and 5T/4. They start SHM at the same time from the mean position. After how many oscillations of the smaller pendulum they will be again in the same phase:

G1 Physics · Accepted Answer

The pendulums are again in the same phase when an integer number of their periods has elapsed: nT=m(5T/4). The smallest integers satisfying 4n=5m are n=5 and m=4. Thus the smaller-period pendulum completes 5 oscillations. Correct answer: A.