Physics In Ice Hockey

Skating in hockey is really all about physics: more specifically, it's about forces and friction. Because the ice is very slick and has a low coefficient of friction (both static and kinetic), a hockey player cannot accelerate by simply pushing backward with their foot, like we do when we walk (where the friction is greater and allows the ground to push us forward when we push on it). In order to generate force and accelerate forward, a hockey player must instead push off at an angle perpendicular (or as close to 90 degrees as possible) to the location they want to go. By angling their ankle and skate blade closer to the ice, they are able to dig into and push off the ice (supply a force into the ice), which subsequently generates a force that is perpendicular to their foot and is in the opposite direction of the force the skater exerts. This is the normal force that the ice supplies. By increasing the angle to 90 degrees (pushing off perpendicular to where they wish to go), they can ensure that most or all of the force generated is in the direction they want to go; this works because normal force is always perpendicular to the ground or surface that receives the applied force, which in this case is the force of the skater pushing their foot and skate blade into the ice.

Physics in Volleyball

Yesterday I went to the women's volleyball game against Loyola. As the game went on I began to think more and more about how gravity and forces play significant roles in this sport. When someone is getting ready to serve, they throw the ball upwards (exerting an upward force) and then their palm makes contact with the side of the ball in the air (exerting yet another force, but this time in the forward direction and partially downwards depending on if the serve has top spin or if it is simply a float serve). Due to gravity, the ball's height will decrease as it reaches the other side of the net. Depending on the magnitude of the force exerted on the ball by the server, the ball could accelerate downwards much more quickly than expected, which makes the ball more difficult to pass for the receiving team. When the passers forearms come in contact with the ball, there is both and upward and a forward force at some angle theta so that the ball will appropriately travel into the hands of the setter. Once the ball reaches the setter, there is a very brief moment in which the setter allows the ball (being acted on by the force of gravity) to sink into her hands so that she may exert a strong upward and forward force to set the ball for one of the hitters. The greatest force exerted by any player in the game is when a hitter goes to hit the ball over the net in order to try and get a kill, and ultimately, a point. When a hitter is hitting, they attempt to exert as much of a downward force as possible. This downward force is always accompanied by some sort of forward force so as to avoid directly hitting the ball into the net. While the hitters are exerting this great downward force, gravity is also working in their favor in the same downward direction. The velocity and acceleration of the ball constantly changes throughout the game as passes decrease the velocity and overall acceleration of the ball and hits increase the velocity and acceleration of the ball. When velocity and acceleration increase as a result of a force exerted by a hitter it is much more difficult for the receiving team to react quickly enough to pass the ball and retaliate in a similar manner.