When you throw a ball upwards, its speed decreases while it is going up. Here's why:

* Gravity: The primary force acting on the ball is gravity, pulling it downwards.

* Opposing Motion: As the ball travels upwards, gravity works against its upward motion, slowing it down.

* Zero Speed at the Peak: Eventually, the ball's upward speed will be completely canceled out by gravity. At this point, the ball momentarily stops moving before it starts to fall back down.

In short: The ball's speed decreases continuously as it travels upwards due to the constant force of gravity acting against its motion.