eli5 if a pitcher stands on top of a train going 50mph and throws a pitch that goes 100mph. does the ball move at 150mph?

Question

eli5 if a pitcher stands on top of a train going 50mph and throws a pitch that goes 100mph. does the ball move at 150mph?

In: 1

Answer 1

It depends on what your perspective is. Speed is only meaningful when it’s relative to something else. From the perspective of someone standing still and watching the train go by, yes. From the perspective of the person throwing the ball, no, the ball is only going at 50mph relative to the pitcher. Both are equally correct. This is actually a concept that’s really important in and fundamental to Einstein’s special relativity.