Question

A ball is thrown up with a speed of $9.8m{s}^{-1}$. What is the acceleration while the ball is moving downwards?

Answer 1

1. When an object is thrown up, the only force acting on it is gravity. The acceleration acting on the ball is the acceleration due to gravity which is $9.8m{s}^{-2}$.

2. The acceleration due to gravity is always directed towards the center of the earth and the ball is also moving downwards. As, the direction of the acceleration is the same as the direction of the motion of the ball, thus, the acceleration of the ball while moving downwards is taken as a positive value $g=9.8m{s}^{-2}$.

Hence, the acceleration while the ball is moving downwards is $9.8m{s}^{-2}$.