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Think Like Einstein
Part 1: Adding Velocities

Animation of train example

We begin with a basic concept—one that sets the scene...

You're on a train that's moving forward at 50 mph. You throw a ball in the direction that the train is moving. Relative to you and the train, the ball leaves your hand travelling at 20 mph.

Question: From the point of view of someone standing alongside the tracks, how fast is the ball moving?
  1. 20mph
  2. 30mph
  3. 50mph
  4. 70mph



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