While the gondola is rising at a speed of 2.0 m/s, a passenger in a balloon-supported gondola throws a small ball down at a speed of 5.0 m/s relative to his body. A person who measures the ball's velocity at the instant of release will find that the ball's velocity relative to the ground at that instant is
A) 2.0 m/s, up.
B) 3.0 m/s, down.
C) 3.0 m/s, up.
D) 5.0 m/s, down.
E) 12.8 m/s, down.

Question

Quizplus · Accepted Answer

The initial velocity of the ball relative to the ground is the vector sum of the velocity of the gondola and the velocity of the ball relative to the gondola. Since the gondola is rising at a speed of 2.0 m/s, the initial velocity of the ball relative to the ground is 5.0 m/s - 2.0 m/s = 3.0 m/s down. Therefore, the correct choice is B.

While the Gondola Is Rising at a Speed of 2