Verified Solution • 2025–26 Session moderate

QPages 456-457: Q5: HC Verma: Concepts of Physics - Volume 2 The Special Theory of Relativity Pages 456-457: Q5 Solution: A person travelling in a fast spaceship measures the distance…

⚠️ Common Exam Traps & Conceptual Pitfalls

Students often confuse the moving observer's frame with the proper length frame, incorrectly assuming the spaceship measures the maximum distance. Remember that proper length $L_0$ is defined only in the frame where the endpoints (Earth and Moon) are at rest, so any other inertial frame will measure a contracted length $L < L_0$.

A person travelling in a fast spaceship measures the distance between the earth and the moon. Is it the same, smaller or larger than the value quoted in this book?

Step-by-Step Verified Solution

**Answer:** The distance measured by the person in the spaceship will be **smaller** than the value quoted in the book. **Step-by-Step Explanation:** The distance between the earth and the moon is measured in the earth-moon rest frame, which is essentially the earth frame. This is the proper length L0L_0. For an observer in a fast-moving spaceship, the distance is length-contracted:
L=L01−v2c2<L0L = L_0\sqrt{1 - \frac{v^2}{c^2}} < L_0
Hence, the person in the spaceship measures a smaller distance .

All Questions in this Chapter

QPage 457: Q1 QPage 457: Q2 QPage 457: Q3 QPage 457: Q4 QPage 457: Q5 QPage 457: Q6 QPage 457: Q7 QPage 457: Q8 QPage 457: Q9 QPage 457: Q10 QPage 457: Q11 QPage 457: Q12 QPage 457: Q13 QPage 458: Q1 QPage 458: Q2 QPage 458: Q3 QPage 458: Q4 QPage 458: Q5 QPage 458: Q6 QPage 458: Q7 QPage 458: Q8 QPage 458: Q9 QPage 458: Q10 QPage 458: Q11 QPage 458: Q12 QPage 458: Q13 QPage 458: Q14 QPage 458: Q15 QPage 458: Q16 QPage 458: Q17 QPage 458: Q18 QPage 458: Q19 QPage 458: Q20 QPage 458: Q21 QPage 458: Q22 QPage 458: Q23 QPage 458: Q24 QPage 458: Q25 QPage 458: Q26 QPage 458: Q27 QPage 458: Q28 QPages 456-457: Q1 QPages 456-457: Q2 QPages 456-457: Q3 QPages 456-457: Q4 QPages 456-457: Q5

Related Learning Resources & Exam Preparation

Chapter Practice Bank
Practice all topic-wise questions from The Special Theory of Relativity
Reference Textbook Solutions
Explore complete chapter exercises for HC Verma: Concepts of Physics - Volume 2
Competitive PYQ Question Bank
Browse year-wise authentic previous years' questions with solutions
Authentic CBT Mock Tests
Simulate official exam environment with live timer and percentile scoring