Q121 / 180 · COMEDK 2016 · Physics

A simple pendulum has a period $T$ inside a lift, when it is stationary. The lift is accelerated upwards with constant acceleration $a$. The period

  • Correct answer
    A
    decreases
  • B
    increases
  • C
    remains same
  • D
    becomes infinite

Solution

The time period of a pendulum is given by $T=\frac{1}{2 \pi} \sqrt{\frac{l}{g}}$ When a lift containing a simple pendulum is accelerated upwards with acceleration $a$, then its time period becomes $T^{\prime}=\frac{1}{2 \pi} \sqrt{\frac{l}{(g+a)}}$ Clearly, $\quad T^{\prime} \angle T$ Hence, its time period decreases.

Hence, the correct answer is option: 'A'.

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