A ball is projected upward at time t = 0.00 s, from a point on a roof 70 m above the ground and experiences negligible air resistance. The ball rises, then falls and strikes the ground. The initial velocity of the ball is 28.5 m/s. Consider all quantities as positive in the upward direction. The velocity of the ball when it is 39 m above the ground is closest to
A) -38 m/s.
B) -30 m/s.
C) -23 m/s.
D) -15 m/s.
E) -45 m/s.

Question

Quizplus · Accepted Answer

The correct answer is A because the ball is at its maximum height when it is 39 m above the ground, and its velocity is zero at that point. As the ball falls, its velocity becomes increasingly negative, and when it is 39 m above the ground, its velocity is -38 m/s.

A Ball Is Projected Upward at Time T = 0