Newtons First Law: An object in motion or at rest tends to stay in motion or at rest unless acted upon by an outside force. Before a hockey player takes a slap shot, his entire body needs to rotate to create momentum and energy to deliver enough power for a hard shot. Rotating your body and and following through with your stick delivers much power into the shot than just using upper body strength to hit the puck. Rotational motion throughout the body makes the stick move and proves Newton's first law. 

Newtons Second Law: Newtons second law is basic and anyone who has taken a basic physics course will have heard of this law, to sum it up F=ma. The force applied to an object is a result of its mass multiplied by its acceleration. The force is cause by the rotational motion, The acceleration is a result of how fast the players entire body is rotated and the mass is a combination of the players weight and the stick weight. Rotational motion however replaces linear motion in this case due to the type of motion it is. Rotational motion then turns it into torque which is a product of inertia and angular acceleration. Inertia is a result of a constant multiplied by mass and then radius squared and angular acceleration is a result of linear acceleration divided by the radius. 

Newtons Third Law: Every force has its pair that is equal in magnitude in the opposite direction. This is where following through with your shot will come into maximum efficiency. Following through with the shot is the same as pointing where you want it to go. Hips, upper body and lower body all work equal and opposite. Rotational mechanics is what produces that hardest shot possible.