Here's why:
* As the ball travels upwards:
* Gravity acts downward, causing a downward acceleration.
* The ball's velocity is upwards, but it is constantly decreasing due to the downward acceleration.
* At the peak of its trajectory:
* The ball momentarily stops moving upwards.
* However, acceleration due to gravity is still acting downward.
* As the ball falls back down:
* Gravity still acts downward, causing a downward acceleration.
* The ball's velocity is now downward, and it increases as it falls due to the acceleration in the same direction.
In this scenario, the acceleration due to gravity is always acting in the opposite direction of the ball's velocity when it's moving upwards and in the same direction when it's moving downwards. This results in a slowing down of the ball as it goes up and a speeding up of the ball as it comes down.
