Here's why:
* Friction is a force that opposes motion. It arises from the microscopic interactions between the surfaces of the two objects.
* These interactions involve the molecules of the surfaces bumping into each other. This bumping and jostling increases the kinetic energy of the molecules, which manifests as heat.
Examples:
* Rubbing your hands together quickly will make them warm.
* A car's brakes get hot when they are applied.
* A matchstick ignites because friction creates enough heat to overcome the activation energy for combustion.
Let me know if you'd like to explore other aspects of friction!
