Question

A train is moving along the tracks at a constant speed u. A girl on the train throws a ball of mass m straight ahead along the direction of motion of the train with speed v with respect to herself. Then,

• A. The kinetic energy of the ball as measured by the girl on the train is $\frac{mv^2}{2}$
• B. work done by the girl in throwing the ball is $\frac{mv^2}{2}$.
• C. Work done by the train mvu
• D. The gain is the kinetic energy of the ball as measured by a person standing by the rail track is $\frac{mv^2}{2}$.

Answer 1

Answer: (A), (B), (C)

The kinetic energy of the ball as measured by the girl on the train is $\frac{mv^2}{2}$

Answer 2

The correct answer is/are option(s):
(A): The kinetic energy of the ball as measured by the girl on the train is $\frac{mv^2}{2}$
(B): work done by the girl in throwing the ball is $\frac{mv^2}{2}$.
(C): Work done by the train mvu