Rotation: An object moves in a circle around a point or an axis. Any object (or a system composed of multiple objects) has a center of gravity, and the position of the center of gravity remains unchanged, but the local motion on the object is relative to the center of gravity. This is rotation. For example, the earth rotates around the earth's axis and also around the sun. In mathematics, rotation is a graphic movement.
Objects that translate and rotate in life:
Rotation: windmill, steering wheel, airplane wing, electric fan, bicycle tire, automobile tire, clock, induced draft fan, fan (automobile water tank, computer mainframe, etc.). ), etc.
Elevator, drawer, sliding door, sliding window, etc.