question_answer

A pendulum suspended from the ceiling of a train has a period T, when the train is at rest. When the train is accelerating with a uniform acceleration a, the period of oscillation will           [NCERT 1980; CPMT 1997]

A)            Increase                                 

B)            Decrease

C)            Remain unaffected           

D)            Become infinite

Correct Answer: B

Solution :

                   Initially time period was \[T=2\pi \sqrt{\frac{l}{g}}\].                                          When train accelerates, the effective value of g becomes \[\sqrt{({{g}^{2}}+{{a}^{2}})}\] which is greater than g Hence, new time period, becomes less than the initial time period.