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Concepts Of Physics MCQ Edition [Volume 2]PhysicsThe Special Theory of Relativity

A shop owner measures a suitcase kept on a rack to be 50 cm 25 cm 10 cm . A traveller takes this suitcase on a train travelling with a velocity of 0.6c . If the suitcase is oriented with its length parallel to the train's velocity, determine the dimensions measured by an observer on the ground.

Options

  1. A50 cm 25 cm 10 cm
  2. B62.5 cm 25 cm 10 cm
  3. C40 cm 25 cm 10 cm
  4. D40 cm 20 cm 8 cm

Correct answer

C. 40 cm 25 cm 10 cm

Step-by-step solution

The proper dimensions of the suitcase are L₀ = 50 cm , W₀ = 25 cm , and H₀ = 10 cm . The train is moving with a velocity v = 0.6c . Length contraction occurs only along the direction of motion (parallel to the length). The length measured by the observer on the ground is given by: L = L₀ 1 - v^2 c^2 L = 50 1 - (0.6)^2 = 50 1 - 0.36 = 50 0.8 = 40 cm The dimensions perpendicular to the direction of motion remain unchanged. Thus, the width and height are 25 cm and 10 cm respectively. The dimensions measured by the obs

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