Purpose
The purpose of the lab was to determine the coefficient of kinetic friction, µk, between an object and a surface, and to determine the tension in the string between two objects.
Equipment
Inclined Plane
Wooden box
Weights
String
Motion detector
Wooden box
Weights
String
Motion detector
Procedure
The independent variables were the mass in the wood block (M1) and the mass attached to the end of the string (m2). The independent variables were controlled by using a constant mass for each.
The dependent variable was µ (coefficient of friction).
For the pre-lab theory we had to draw free body diagrams for the forces on both m and M, and solve for acceleration µ and T in variable form.
Second was the actual experiment in which we had to hang M1 on one end of the inclined plane and attach it to M2 which was on the downhill side of the inclined plane itself. After preparing the masses we attached a motion detector to record the position vs time data. Using a program on the computer we were able to graph and analyse the data and find a best fit line.
The dependent variable was µ (coefficient of friction).
For the pre-lab theory we had to draw free body diagrams for the forces on both m and M, and solve for acceleration µ and T in variable form.
Second was the actual experiment in which we had to hang M1 on one end of the inclined plane and attach it to M2 which was on the downhill side of the inclined plane itself. After preparing the masses we attached a motion detector to record the position vs time data. Using a program on the computer we were able to graph and analyse the data and find a best fit line.
Data
The following graphs represent the data that we measured during the lab.
austin_jord_james_trial_1.cmbl | |
File Size: | 19 kb |
File Type: | cmbl |
austin_jord_james_trial_2.cmbl | |
File Size: | 19 kb |
File Type: | cmbl |
austin_jord_james_trial_3.cmbl | |
File Size: | 19 kb |
File Type: | cmbl |
Data Analysis
The slope of these graphs represents the instantaneous velocity at the velocity at that time. To find the acceleration we took the second derivative of the position equations. For the first trail we got an acceleration of .3820 which was a large distance above the acceleration of trials who and three which had accelerations of .2772 and .2806 respectively. Because of this we concluded that there was some additional variable that caused the data to be inaccurate, so we did not use the first trial in our calculations.
Conclusion
During the pre-lab analysis we solved for the coefficient of kinetic friction and found thatµk=a(M2-M1)+mg-mgsin(Θ)
mgcos(Θ)
We also solved for tension and found that T=mg-ma.
We found an error in our first experiment which could have been caused by many factors, for example the block could have been slightly off of the track which would reduce the frictional force causing the block to accelerate at a faster rate therefor skewing the data.
mgcos(Θ)
We also solved for tension and found that T=mg-ma.
We found an error in our first experiment which could have been caused by many factors, for example the block could have been slightly off of the track which would reduce the frictional force causing the block to accelerate at a faster rate therefor skewing the data.