People are moving before the #chair, when people use their own chemical energy to transform into kinetic energy, slowly move, after reaching the balance point, he will accelerate the backward force, people under the speed of inertia There must be a lot,
people will have a moment of movement according to the momentum, and the whole of the #chairs will have a moment after back to the #chair.
Swing can also start swinging in the ground, this is an energy conversion, the chemical energy conversion of the human body is kinetic energy, kinetic energy conversion is potential energy, and then potential energy and kinetic energy conversion.