A passenger walks toward the rear of a moving train.
1. Describe her motion from a reference point on the train.
2. Describe her motion from a reference point on the ground.
Answer (2)
If the train is moving from Point A to Point B, and this motion we arbitrarily deem "forward", then from the reference point of the train, she will be moving backward. From an external reference point, she will be moving in the same direction as the train, but with a lessened velocity.
The passenger walking toward the back of a moving train appears to move backward from the reference point of the train, while from the ground reference point, she moves forward but at a lesser speed than the train. The calculation for her ground speed is the train's speed minus her walking speed. Thus, her effective ground speed can be determined based on both speeds.
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