Why do things heat up like rubbing your hands fast or brakes on a car? How does stuff heat up in general and why is that?

Question

So ive wondered what happens exactly that causes our hands to heat up when you rub them really fast together or why do brakes heat up when used. Why does stuff in general heat up when its put under stress or when its at a high speed and getting slowed down.
Why is it that it all heats up? Why does it not just stay at the same temperature?

Also why do CPU on a PC heat up that much? There is nothing moving in it to make it hot.

In: Physics

Answer 1

Simple answer is energy, that you are adding to an object. In the case of rubbing things together, you’re adding energy via friction, and in the case of computers, you’re adding electrical current energy.