Coefficients of Kinetic and Static Friction

Purpose:
The purpose of the lab is to develop a technique to find the coefficients of static and kinetic friction and then test the accuracy of the coefficients of friction.

Equipment Used:

One block with felt on the bottom of it will have a string attached to it that goes to a cup that will have water filled into using a plastic pipet. When the block with the felt starts to move then the weight of the water and the cup should be equal to the static frictional force of the felt block. The mass of the block and the cup with water will then be weighed on the scale. The same procedure will be done with the force sensor, the only difference is that the coefficient of kinetic friction will be calculated. The inclined plane with the pulley will be used to calculate the coefficient of static and kinetic friction. If the coefficient of kinetic friction is reliable then having a mass hanging off of a pulley the acceleration of the system could be calculated.

Data Collected:
mass of block 1= 108.1 ±.1g, F_pull1= .2271 ±.1N
mass of block 2+1= 249.3 ±.1g, F_pull2= .8470 ±.1N
mass of block 3+2+1= 368.2 ±.1g, F_pull3= 1.213 ±.1N
mass of block 4+3+2+1 = 495.7 ±.1g, F_pull4= 1.484 ±.1N
The angle of the inclined plane when finding the coefficient of static friction between the felt and the table top was 19, the coefficient of static friction was calculated as .3443
The angle of the inclined plane when finding the coefficient of kinetic friction between the felt and the table top was 24, the coefficient of kinetic friction was calculated as .3441, the coefficient of kinetic friction appears to be too high however it wasn't noted during the time of the experiment.

Calculations:
The coefficient of frictions for the first part were found by dividing F_pull1/Normal force

To test the coefficient of kinetic friction, a mass of known mass was held over a the edge of the inclined plane and the mass of the block will accelerate. If the coefficient of fiction was reliable then the calculated acceleration should be close to the measured value.

Conclusion:
The coefficient of kinetic friction that was determined in the last set of calculations was not very reliable. The calculated acceleration was .2618m/s² but the measured value was .5541m/s² which is a big difference. It is over a -50%, a huge margin of error.

Sincerely,

Swaggy C