3 Experiment Lab 3 Introduction:
The purpose of this memo is to test whether or not surface area has anything to do with
the frictional force between two objects. We used a system of wooden blocks and pulleys to determine static friction. With this information and depending upon the block set up we can determine what the frictional force acting upon the objects is. We had two wooden blocks of roughly the same mass and put them on a track. With this we attached them together with a string and put a string around a pulley attached to a mass to determine the force needed to overcome static friction. Results: Maximum surface area: We found out that the mass that was needed to move the block system was 80 grams. With this we can solve the static frictional force which is < (.08 kilograms+.045 kilograms)-mass of weight system- X 9.8 and we find that the force is 1.22 N. We then just stacked the blocks on top of each other. Then we just placed the string around the pulley and tried at it again the results for that part were, the mass needed to move the system was 54 grams. So using our formula that static Frictional force < (.054 + .045) X 9.8 and that is .97119N. Results: We found that the mass needed to move this was 60 grams. We can find the static frictional force to be (.060 + .045) X 9.8 = 1.04967N.
Velocity of blocks
0.1 0.08 0.06 0.02 0.04 0 Velocity of blocks M/S
Seconds
This is the average velocity of the blocks. We can see here that there were parts were the frictional force was greater than others; hence the great gap in some of the information.
This shows to us that the coefficient of friction is distorted by the blemishes and marking on the metal track. With this we found that the greater the surface area the greater the frictional forces. If there was no friction we could say that the acceleration would be Weight of the mass at the end of the pulley/ the mass of the system, would be the acceleration of the system so could say that the acceleration would be 3.5 m/s, 2.82 m/s, and 3.05 m/s respectively. We measured the coefficient of friction to be Frictional force/normal force to be approximately .7, unfortunately our testing conditions weren't the best. Our wood had many parts that were uneven didn't have perfect center of mass and the metal was also rougher in some parts than other. As the graph showed us, the velocity didn't show us a constant line or anywhere close to one. We can calculate that the frictional force is somewhere in between .5 newtons and .8 newtons. Positively this wear and tear on the track shows us that wear and tear on the brake pads will definitely affect the frictional force and thus the stopping power of the street slider.