relative velocity and work done by the train
A train moves along the tracks at a constant speed u. A woman on the train throws a ball of mass m straight ahead with a speed v with respect to herself.
a) What is the kinetic energy gain of the ball as measured by a person on the train?
b) By a person standing by the railroad track?
c) How much work is done by the woman throwing the ball and the train?
d) how much work is done by the train?