A N"ICE" Way to Find the Coefficient of Friction

There is no better activity to do on a cold winter’s day than ice skating!  As we know, ice is good
for skating because it has a low kinetic friction coefficient between it and other materials,
making it slippery.  But, just how low is this number?  I decided to use a hockey puck to figure
this out!

As you can see in the video, the hockey puck is hit by the stick with some force, which causes it
to slide on the ice until it hits a second hockey puck.  To determine the final velocities of both the
hockey stick and puck just before it hits the second puck, as well as the distance the puck
traveled and the time that the hockey stick traveled, I used Logger Pro.

Once I had my data, I used kinematics to solve for the accelerations of the hockey puck
and stick.

Hockey Puck	Hockey Stick
x = 0.5836 m vi = 0 m/s vf = 0.1366 m/s a = ?	t = 1.5 sec vi = 0 m/s vf = 0.119 m/s a = ?
vi2 = vf2 + 2ax 0.13662 = 02 +2a(0.5836) a = 0.016 m/s2	vf = vi + at 0.119 = 0 + 1.5a a = 0.0793 m/s2

Then I drew a free body diagram for the hockey puck.

ΣFy = N - Fg = 0

ΣFx = Fstick - fk = ma

In order to find the force of the stick and the force of the friction, I used the masses of the
hockey puck and stick.  

Hockey Puck	Hockey Stick
Mass: 0.156 kg	Mass: 0.538 kg

Fstick = 0.538 * 0.0793 = 0.0427 N

Fstick - fk = ma

0.0427 - fk = 0.156 * 0.016

fk = 0.0402 N

Finally, I used the Normal force to find the coefficient of kinetic friction between the ice and
rubber.

N - Fg = 0

N - 9.8 * 0.156= 0

N = 1.5288

fk = N

0.0402 = 1.5288

= 0.026

Thus, the coefficient of kinetic friction between ice and the particular type of rubber of which
the hockey puck was created is 0.026.

Special thanks to Matthew Poirier, Shaila Murthy, Victoria Hennemann, and Kathryn Grupp for helping with the video!