A ball of relatively low density is thrown upwards.Because of air resistance the acceleration while traveling upwards is −10.8 m/s².On its trip downward the resistance is in the opposite direction,and the resulting acceleration is −8.8 m/s².When the ball reaches the level from which it was thrown,how does its speed compare to that with which it was thrown? A)It is greater than the original speed upward. B)It is the same as the original speed upward. C)It is less than the original speed upward. D)Without knowing the original speed,this problem cannot be solved.

Question

Quizplus · Accepted Answer

When the ball is thrown upwards, the acceleration due to air resistance is in the opposite direction of the velocity, so it slows down. When it reaches its maximum height, its velocity is zero. On the way down, the air resistance is in the same direction as the velocity, so it accelerates. However, the acceleration is not as large as the acceleration due to gravity alone (-9.8 m/s^2), so the ball is still slowing down. Therefore, the speed of the ball when it reaches its starting height is less than the speed with which it was thrown upwards.

A Ball of Relatively Low Density Is Thrown Upwards