Conceptual Physics (12th Edition)

Published by Addison-Wesley
ISBN 10: 0321909100
ISBN 13: 978-0-32190-910-7

Chapter 35 - Think and Explain: 51

Answer

The light beam has exactly the same speed, c, relative to the ground as it has relative to the moving train. This is different from the ball's behavior, which appeared to move faster when viewed from the ground.

Work Step by Step

The speed of light is the same for all observers, in all reference frames. This is Einstein's second postulate of special relativity.
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