To conduct the experiment, the disc is driven by manually applying a force in the direction
normal to its radius for a short period of time. The force initiates the rotation and the disc is
left to rotate freely. The only force that exists during such motion is frictional force that slows
down the disc. A video of the freely rotating disc is made. The black marker is our tracked
point. We can then acquire the angular speed from Tracker. As a result, we can derive the
linear coefficient of rotational friction from linear regression analysis based on equation (2)
and, therefore, it is possible to calculate frictional torques at various angular speeds from
equation (1).