Newton's First Law an object in motion stays in motion and an object at rest stays at rest unless acted upon by an unbalanced force. Inertia is the tendency of all objects to resist a change in motion. An object will not move until a force makes it move. There is a natural tendency of objects to keep on doing what they're doing. All objects resist changes in their state of motion. Without an unbalanced force, an object in motion will maintain this state of motion. Objects with more mass have more inertia. The objects with more mass (and inertia) will require more force to change its motion. Video: Laws of Inertia: Definition & Formula
Newton's Second Law the acceleration of an object (how much it moves) depends on the objects mass (the stuff inside) and the amount of force applied.
Newton's Third Law for every action there is an equal and opposite reaction.
Which does more damage: a car hitting a wall at 100 mph, or 2 cars colliding at 50 mph? In this experiment the mythbusters find out and Newton's Laws are proven to be correct