Physics of a Hockey Slapshot

 I used to play hockey goalie and would have to deal with the 80+ mph slap shots coming from only 15 feet away. I never understood the physics behind this high intensity tactic used by players to produce extremely fast paced shots. Now I understand that this technique uses an elastic collision in which the stick hits the ice before the puck to create stored spring energy that is transferred to the puck as kinetic energy. This produces the high velocity of the puck. 

Hockey players needed new ways to get the puck passed the goaltender, and what better way to do that than with the fastest way to shoot a puck. A slap shot allows a player to get the maximum amount of power and energy into the puck to produce its maximum velocity. The player will raise up his stick, swing it down to make contact with the ice, create a bend in their stick, and make contact with the puck to transfer energy through the system and increase its velocity. 

The picture above of the hockey player shows the obvious bend in the stick as it makes contact with the puck on the ice surface. The physics behind why this shot produces high puck speeds is actually very cool. When the player raises their stick in the air, they are creating gravitational potential energy that is stored in the stick. As it is swung down using kinetic energy, it hits the ice before hitting the puck and is creating a bend in the stick which puts spring, or elastic, potential energy into the stick. Upon decompression of the stick as it makes contact with the puck, the energy is transferred to the puck as kinetic energy. Because energy is conserved in this action, the sum of the energies can be equalled to zero and one can analyze the speed produced from the system. The energy put into the stick to create the bending comes from the weight of the player and the bend can be controlled by how much is put in. If a player puts a lot of his/her weight into the stick, it creates a large bend and will produce a higher transfer of energy into the puck. A higher transfer of energy will give a faster velocity of the puck as the elastic collision has more energy stored. Zdeno Chara is the tallest player in the NHL, standing at 6’9” and weighing 260 lbs, and he can transfer a lot of power and weight into his stick. With this power, he is able to produce a shot at over 108 mph and still holds the record in the NHL to this day. The energies in the system, while some are lost due to sound and frictions, allow for the most amount of energy to be transferred from the player to the stick to the puck to cause a maximum velocity shot. 

Work Cited:

Cross, Rod, and Crawford Lindsey. “The Slap Shot in Ice Hockey.” American Association of Physics Teachers, American Association of Physics Teachers AAPT, 1 Jan. 1970.

“Shooting.” The Physics behind Hockey, physicsofhockeyproject.weebly.com/shooting.html.