So you're telling me, this guy was on a train, and the train was moving 100 mph. Since the man was on the train, he was also moving 100 mph. But then he walked from the front of the train to the back, and then to the front again?
So he'd have to slow down so that he was moving
less than 100 mph to get to the back of the train, and then speed up so that he was moving
more than 100 mph to get back to the front of the train.
So you're telling me this guy can walk more than 100 mph?
Uh-huh, sure.