Cách sử dụng
Friction is a force that happens between two objects that are touching each other. It makes it harder for them to move against each other. For example, when you try to push a heavy box across the floor, friction between the box and the floor makes it harder to move. Friction happens in many places, like when you rub your hands together or when you walk on the ground. In general, friction can slow things down or make them harder to move, but it can also be useful. For example, we use friction to help stop cars and bicycles when we brake.