Kinetic friction Coefficient of Wood on Aluminum

 

Purpose for this lab is to find the coefficient of friction from the fricitonal force and the normal force.

Proceudure: We used weights, a cart, a meter stick, a timer, and a cart track. We measured the lentgh and the height of the track and the mass of the cart. To get our graphs, we measured the time which cart falls down the track at varying heights with varying masses. We measured for unceartinty as well, with one consisting of changing height and a constant mass, and the other one consisting of changing the mass and a constant height. We used all these data to find the coefficient of friction for wood on aluminum.

Calculated Friction and Normal Force

Friction vs. Normal: Constant Mass

Uncertainty: +/-0.193

Friction vs. Normal: Constant Height

Uncertainty: +/-0.0245

What is the coefficient of kinetic friction for wood on aluminum? How does this compare to your prediction?

The calulcated coefficient of kinetic friction is 0.235. The slope of the frictional force vs. normal force graph relates to the coefficient of friction. We can get the coefficient of direction by f/N. Predicted range was 0.2 - 0.6 and the calculated values mathces the expectations.

What are the limitations on the accuracy of your measurements and analysis? Over what range of values does the measured graph match the predicted graph best? Where do two curves start diverge from one another? What does this tell you?

Human's reaction time of starting the timer and releasing the cart and the thin strip of plastic which prevented wood from making a direct contact with the aluminum limits the accuracy. The range of masses over a constant height provides the most accurate analysis given the prediction range 0.2  to 0.6. After 0.47kg the calculated values begins to diverge from the predicted values. This shows that there are additional factors that are not accounted for in the current experiment which applies non-negligible influence.