THE PHYSICS OF HOCKEY

The Lacrosse Style Goal

Video Example

THE PHYSICS OF HOCKEY

For example , if in the video Mike Legg is going to try follow a circular path with a radius of 4 feet he will need to accelerate the puck fast enough so that it over comes the force of gravity on the puck (13.72N since F=ma so F=(1.4kg)(9.8m/s^2)). So Legg needs a force of around 14N to make the shoot successful. Using the F=ma equation to he needs to have a centripetal acceleration of 10m/s^2 (a=m/F). Then using the centripetal acceleration equation (a=v^2/r so v=(ar)^(1/2)) Legg needs the puck to initally move at about 6.3m/s for the puck to stay on his stick for the entire shot.

The Lacrosse Style Goal

Centripetal Force and Acceleration

Centripetal Force and Acceleration play huge roles in pulling off the Lacrosse Style Shot because the centripetal force has to be large enough to overcome gravity or the puck will fall off the stick.

The centripetal force equation is Fc=m*ac where ac is the centripetal acceleration and m is the mass in kilograms.

The centripetal acceleration equation is ac=v^2/r where v is the velocity and r is the radius

How it Works

Real World Physics says, "To begin the move, Mike Legg orients the puck on its edge so that it touches the blade of his stick head on. He then guides the puck along (using the blade of his stick) such that it follows a curved trajectory, as shown. This curved trajectory causes the puck to experience centripetal acceleration. The centripetal acceleration points towards the center of curvature of the curve, in the direction of the red arrows (shown in the picture). This centripetal acceleration in turn causes the puck to "push" against the blade hard enough so that it doesn't fall off due to gravity."(Real World Physics)

Collisions

Even though there are two types of collisions, elastic and inelastic, collisions in ice hockey are all elastic because both objects that collide separate. After the collision the combined velocity and momentum of the objects stay relatively the same. Some velocity is lost during the collision due to friction but that velocity is minsicule.

Energy

Friction in Hockey

The Law of the Conversation of Energy plays a large role in hockey whenever a check occurs becasue the energy has to stay constant(Ei=Ef) even through the transfer during the hit.

Friction plays a large role in hockey because every time a player takes a stride they are overcoming friction and everytime a shot is taken or a pass is made friction is slowing down the velocity of the puck. In hockey the force of friction is relatively low because the coefficient of friction is about .15. In perspective the coefficient of friction of rubber on a road is .7

Friction example

Collisions, Momentum and Energy

A 1.4kg puck is passed with an unknown acceleration if the coefficient of friction is .15 what is the applied acceleration of the puck if the net force is 8N?

Fnet=Fa-Ff so Fa=Fnet+Ff or

MaAa=Fnet+U(coefficent of ction)MfAg so Aa=(Fnet+UMAg)/(M) so

Aa= {8N-{(.15)(1.4)(9.8)}}/(1.4)

so Aa= 2.24 m/s^2

Applied acceleration is

2.24 m/s^2

Momentum

Friction

Sources

In hockey, the law of conservation of momentum applies because when one object (i.e. a player, or stick) hits another object (i.e. a player or puck) the system momnetum will stay constant (pi=pf)and some momentum will be transfered from object 1 or object 2 (p1i+p2i=p1f+p2f)

"Centripetal Acceleration." Centripetal Acceleration. N.p., 9 Oct. 1997. Web. 30 Mar. 2014. <http://theory.uwinnipeg.ca/physics/circ/node6.html>.

"Momentum - Physics of Hockey! Sliding Friction and Momentum on ICE 2.0." Physics of Hockey! Sliding Friction and Momentum on ICE 2.0. N.p., n.d. Web. 30 Mar. 2014. <http://www.hockeyphysics.com/momentum.html>.

Nave, R. "Centripetal Force." Centripetal Force. N.p., n.d. Web. 30 Mar. 2014. <http://hyperphysics.phy-astr.gsu.edu/hbase/cf.html#cf>.

Normani, Franco. "The Physics Of Hockey." Real World Physics Problems. N.p., n.d. Web. 23 Mar. 2014. <http://www.real-world-physics-problems.com/physics-of-hockey.html>.

"Sliding Friction." Sliding Friction. Western Washington University, n.d. Web. 30 Mar. 2014. <http://faculty.wwu.edu/vawter/PhysicsNet/Topics/Dynamics/Forces/FrictionalForce.html>.