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Question: 

A friend speeds by you in her spacecraft at a speed of 0.720c. It is measured in your frame to be 4.80 m long and 1.35 m high.

  1. What will be its length and height at rest?
  2. How many seconds elapsed on your friend’s watch when 20.0 s passed on yours?
  3. How fast did you appear to be traveling according to your friend?
  4. How many seconds elapsed on your watch when she saw 20.0 s pass on hers?

Source: Giancoli, Douglas C., Physics: Principles with Applications, 7th Edition, 2014.

Quick Answer: 
  1. $6.92 \textrm{ m}$
  2. $13.9 \textrm{ s}$
  3. $0.720c$
  4. $13.9 \textrm{ s}$

Giancoli 7th Edition, Chapter 26, Problem 9

(3:46)

Chapter 26, Problem 9 is solved.

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