JEE Main & Advanced
Physics
Simple Harmonic Motion
Question Bank
Simple Pendulum
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.