Newton’s third law
Forces don’t act in isolation; each is always accompanied by another force that pushes or pulls in the opposite direction.
When pushing a chair across the floor, for example, not only does one exert a force that moves the chair, but the floor exerts another force—friction—opposing the push.
Some examples of Newton’s third law in action include a car’s wheels push backward on the ground, making use of the road’s friction force and moving forward; or a bird’s wings push air down and back to generate lift and fly forward.
