Estimating the Coefficient of Friction Between a Rolling CD Wheel and Wooden Floor

The friction between two materials can change significantly based on how they are interacting. For a CD wheel rolling on its edge across a wooden gym floor, the type of friction we’re dealing with is rolling friction (or rolling resistance), not sliding friction. Rolling friction is generally much less than sliding friction and depends on factors such as the materials in contact, the shape of the objects, and the smoothness of the surfaces.

Even though it’s not as straightforward as measuring sliding friction, we can estimate the coefficient of rolling friction (μr) between the edge of a CD and a wooden floor through a simple experiment:

1. Create a ramp: You can create a ramp using a flat and smooth board. Make sure one end of the ramp is elevated, and the other end is on the wooden gym floor. The angle of the ramp can be adjusted using books or blocks.
2. Roll the CD: Starting from the top of the ramp, let the CD roll down and onto the flat wooden floor. The CD should be rolling on its edge.
3. Measure the distance: Once the CD has come to a stop, measure the distance it rolled across the wooden floor after leaving the ramp.
4. Repeat and average: Repeat the experiment several times to get an average roll distance.
5. Calculations: The rolling friction can be calculated using the formula for motion: d = 0.5at^2.
   
   Here, ‘d’ is the distance traveled (which you’ve measured), ‘t’ is the time taken (which could be measured with a stopwatch), and ‘a’ is the acceleration. However, because the CD slows down due to friction, the acceleration is actually negative – it’s a deceleration. Once you have the deceleration, the coefficient of rolling friction can be approximated as μr ≈ -a/g, where ‘g’ is the acceleration due to gravity.

Keep in mind that this method provides an estimate of the coefficient of rolling friction. Several factors can influence the outcome, including the evenness of the floor, the exact material composition of the CD and the wooden floor, and the precision of your measurements. However, it does provide a good starting point for understanding how the CD wheel interacts with the wooden floor.