9/21/16: Friction Forces

Title: Modeling Friction Forces
Purpose: The purpose of this lab is to model static and kinetic friction with various experiments.
Apparatus:
Experiment 1

Experiment 2:

Experiment 3: 

Experiment 4: 

Experiment 5:

Theory: 

Exp. 1: We place a block on a surface and slowly add weights to the end of a string to the point where it just starts to move in order to find the coefficient of static friction. This is repeated with multiple blocks. 

Exp. 2: We attach the block to a force sensor and pull with a constant force to find the coefficient of kinetic friction. This is repeated with multiple blocks. 

Exp. 3: We place the block on the surface and raise it to the angle where it just begins slipping. We use this to find the coefficient of static friction. 

Exp. 4: We attach a motion detector to the top of the incline and place the block so that it will slip down the incline to find the coefficient of kinetic friction. 

Exp. 5: We use the coefficient found in Exp, 4 to find the acceleration of the block when enough weights are placed on it to just get it to move. 

 

Data/Graphs: 

Exp. 1

Exp. 2:

Exp. 3:

Exp. 4:

Exp. 5: 

Analysis: 

Exp. 1: When we plotted the static friction vs. Normal force, we got 0.4775 as a coefficient of static friction. 

Exp. 2: When we graphed the kinetic friction vs Normal force, we got 0.2999 as a coefficient of kinetic friction. 

Exp. 3: The angle at which it started slipping was 26°, and with that we found coefficient of static friction to be 0.488. 

Exp. 4: The angle we measured at was 27°, the acceleration was 2.503 m/s^2, and with that we found the coefficient of kinetic friction to be 0.222. 

Exp. 5: With the coefficient of kinetic friction we found in 4, we used it to find the acceleration of the mass, which was 1.81 m/s^2, slightly different from the calculated 1. 462 m/s^2. 

Conclusion: 

The numbers we calculated theoretically did not vary much from the actual measured results, which meant that we were successful in completing this experiment. Some rooms where errors may have occurred is the when placing the masses to move the block, as the block would move if the weights were placed too fast. Another place where errors could occur was that the place where we placed the block was only a relative position. We did not place the block at the exactly same place every time.