Newton’s second law
As alluded to in Newton’s first law, in order to move, an object needs a force. Generally, a force is a push or pull. For example, the front door needs a push before it can open. Newton’s second law states that a force depends on the mass of an object exerting that force and its acceleration.
Quickly pushing a hand forward to open the door will create a much more forceful entrance than if the same person slowed their approach.