MCQ
A pendulum is swinging in an elevator. Its period will be greatest when the elevator is
  • A
    moving upwards at constant speed
  • B
    moving downwards
  • C
    moving downwards at constant speed
  • accelerating downwards

Answer

Correct option: D.
accelerating downwards
d
Time period of a simple pendulum is given by

$T=2 \pi \sqrt{\frac{l}{g}}$ or $T \propto \sqrt{\frac{l}{g}}$

when the elevator is accelerating downwards, the net gravitational acceleration is $(g-a),$ so, the time period when elevation is accelerating downwards, is greatest.

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