Newton's First Law of Motion: Law of Inertia Newton's first law or the law of inertia states that an object at motion will stay in motion unless acted upon by an external force and that an object at rest will stay at rest unless acted upon by an external force.
For example, if no force is exerted on the hockey puck, it won't move. If you exert a force on the hickey puck it will slide on the ice and it will eventually stop due to friction from the ice. It will also stop if it hits another hockey stick or the goalpost.
Newton's Second Law of Motion (f=ma) The second law of motion states that the acceleration of an object as produced by the net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.
The acceleration of a baseball as produced by the baseball bat is directly proportional to the magnitude of the baseball bat, the ball will go in the same direction the bat is directed towards and the acceleration of the ball will be inversely proportional to the mass of the ball.
Newton's Third Law of Motion: For every action, there is an equal and opposite reaction
When a tennis player hits the ball, the racket exerts a force on the ball and the ball exerts an equal and opposite force on the racket. The racket exerts the action force and the ball exerts the reaction force which is felt during the time that the racket strikes the bat. If the same tennis ball were to hit the floor, the ball would exert a force on the floor and the floor would exert an equal and opposite force on the ball.