Physics of Ice Hockey
What concepts are involved?

By Víctor Ontiveros

Here's some background information about ice hockey

The NHL (National Hockey League) is often referred to as the 4thmost popular sport of the professional sports in North America. Hockey, in North America, has climbed the rankings in the past few decades. In 1985, Hockey was ranked as the 11th most popular sport according to a servey done by Harris Interactive. With hockey becoming more popular here in North America as time goes on, let's take a look at the physics behind this Olympic sport.

The physics of skating on the ice

The ice is prepared in such a way that there is very low friction and the blades on the skates of the players can dig into the ice to create friction to slow down or change direction. For a player to gain momentum, they exert a force perpendicular to the ice. According to Newton's third law, (every action has an equal and opposite reaction) the ice is exerting a force back onto the player, giving them momentum. Experienced players will lean forward while moving. This is to prevent the player from falling backwards due to torque, the player moves his center mass forward to create a counter-torque, balancing the player.

The puck

There isn't much to say about the puck. However, it is the object that has the most velocity and experiences the most collisions. The puck is frozen before the game. This reduces friction on the ice, allowing it to travel faster without sticking to the ice. From a player's point of view, this is a very helpful attribute of the puck, the player can maintain his momentum without having to stop to hit the puck again. The player is able to keep his kinetic and potential energy constant since the puck has low friction. This allows him to more easily transfer energy from his body to the puck.

The hockey stick

The hockey stick has a curvature at the end. This is crucial in sending the puck far at very high speeds. When the puck comes into contact with the hockey stick, it stays in contact with it longer as it glides along the curvature before being sent flying. Although the time that the puck is in contact with the stick is a fraction of a second, thanks to impulse, it does make a difference in har far and fast it goes. The puck will sit for the brief duration of impact before flying off, since it has more time in contact with the blade, more force can be applied as per the impulse momentum theorem, the longer that an object has a force applied, the greater its change in momentum.
Impulse: FΔt = Δp (force times the amount of time the puck is in contact with the hockey stick is equal to the momentum the puck will have.)

Physics of hockey in general

There are inelastic collisions all the time in hockey as well. When the hockey puck hits the stick or when a player bumps into another player, sending him sliding along the ice. This can all be modeled by one equation:
m1v1i + m2v2i = (m1 + m2)vf

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