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NEET2019PhysicsMotion in One DimensionActual

A person standing on the floor of an elevator drops a coin. The coin reaches the floor in time t₁ if the elevator is at rest and in time t₂ if the elevator is moving uniformly. The which of the following option is correct?

Options

  1. At₁ t₂ depending upon whether the lift is going up or down
  2. Bt₁ < t₂
  3. Ct₁>t₂
  4. Dt₁=t₂

Correct answer

D. t₁=t₂

Step-by-step solution

Let h be the height through which the coin is dropped. Then, according to the equation of motion, it is given as aligned h = ut + 1 2 gt ^2 t = 2 ~h ~g [ u =0] t 1 g aligned As the elevator is moving uniformly i.e. its velocity is constant, so the acceleration is zero. Relative acceleration of the lift when it is either moving upward or downward is given as, g ^ = g a = g 0= g Hence, the time for the coin to reach the floor will remains same i.e. t₁=t₂ .

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