Question

From a building 2 balls A and B are thrown such that A is thrown upward and B is thrown downward. If vA and vB are their respective velocities on reaching the ground, then _____________

(a) vB is greater than vA

(b) vB = vA

(c) vB is lesser than vA

(d) Their velocities depend on their masses.

This question was posed to me in a national level competition.

Question is taken from Acceleration due to Gravity topic in section Laws of Motion of Engineering Physics I

Answer 1

Correct option is (b) vB = vA

To explain I would say: Suppose the ball A is thrown upward with velocity u and ball B is thrown downward with same velocity u. After reaching the highest point the ball A comes back to its position with the same velocity in downward direction. As the 2 balls fall from the same position with the same velocity, both attain the same velocity on reaching the ground.