Here's why:
* Deceleration is simply a decrease in speed, or a negative acceleration.
* Friction always opposes motion. It acts in the opposite direction to the object's movement.
* This opposing force slows the object down, resulting in a decrease in speed.
Example: Imagine pushing a box across a rough floor. Friction between the box and the floor acts in the opposite direction to your push, slowing the box down. This slowing down is deceleration caused by friction.
