Here's why:
* Friction opposes motion: Friction acts in the opposite direction of movement, slowing down or preventing motion altogether.
* It's everywhere: Friction occurs between any two surfaces in contact, whether it's between your shoes and the ground, a car's tires and the road, or even between the air molecules and a moving object.
* It converts energy: Friction doesn't simply disappear; it converts kinetic energy (energy of motion) into other forms, usually heat. That's why your hands get warm when you rub them together.
While other forces like gravity can also cause things to stop (like when you throw a ball up), friction is the most common and ubiquitous force that brings things to a halt.
