Newton's first law states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. It is also known as the law of inertia. Examples given are a hockey puck slowing down due to friction on the ice and a kicked ball in space continuing forever without air resistance or gravity. Newton's second law explains that acceleration is produced by an unbalanced force acting on an object, with greater force needed to accelerate objects with greater mass. Pushing a truck requires more force than pushing a car. Newton's third law states that for every action there is an equal and opposite reaction, such as a boat moving backward when a person jumps