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?

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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

Heat is the random movement of atoms in a material. When you rub it you are pushing on those atoms and making them move, like hitting pegs with a bowling ball.
CPUs heat up because of electrical resistance. When electricity flows through something, you have lots of electrons flowing through the material and hitting the atoms, making them move, aka, heating them up.

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.

Heat is caused by atoms vibrating (and randomly rubbing against each other) by rubbing your hands together you’re (simply put) recreating that process