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QPage 457: Q9: HC Verma: Concepts of Physics - Volume 2 The Special Theory of Relativity Page 457: Q9 Solution: If the speed of a rod moving at a relativistic speed parallel…

⚠️ Common Exam Traps & Conceptual Pitfalls

Students often incorrectly assume that relativistic mass and length change linearly with velocity, leading them to select options claiming mass doubles or length halves. Remember that both quantities depend on the Lorentz factor $\gamma = \frac{1}{\sqrt{1-v^2/c^2}}$, which is non-linear; thus, doubling velocity does not result in a simple doubling or halving of these properties.

If the speed of a rod moving at a relativistic speed parallel to its length is doubled,

Multiple Choice Options

  • A the length will become half of the original value
  • B the mass will become double of the original value
  • C the length will decrease
  • D the mass will increase

Step-by-Step Verified Solution

**Answer:** (c), (d). **Step-by-Step Explanation:** If speed doubles, length decreases further (c) and mass increases further (d).

All Questions in this Chapter

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