A ball is projected upward at time t = 0.0 s,from a point on a roof 60 m above the ground.The ball rises,then falls and strikes the ground.The initial velocity of the ball is 28.4 m/s.Consider all quantities as positive in the upward direction.At time t = 4.3 s,the acceleration of the ball is closest to: A)zero B)+5 m/s² C)+10 m/s² D)-5 m/s² E)-10 m/s²

Question

Quizplus · Accepted Answer

At time t=4.3s, the ball has already reached its maximum height and is on its way down. Therefore, its acceleration is -g, which is approximately -10 m/s^2 (assuming no air resistance). Since all quantities are positive in the upward direction, the acceleration is considered negative, so the closest choice is E, -10 m/s^2.

A Ball Is Projected Upward at Time T = 0