Apparatus: A Pulley, a string, a block of wood(mass), a cup, and water. I know it may sound like an off set up but this is how we set it up to record the data we were looking for.
How This Was Used: First we weighed the block to determine the mass of the block. Next we tied the mass to a string, revolved it around the pulley, and tied the other end to the cup. After we inserted water into the cup until the block started to move. Once we found the breaking point we weighed the cup full of water and recoded all of this data. We repeated the process for the mass of 2 blocks, 3 blocks, and four blocks and recorded all of the data.
What we did with this data: We used this data to find the normal force between the table and the block. We also used this data to determine the maximum static friction between the block and the table.
We then plotted this data in logger Pro by making a maximum static friction Vs. Normal force graph. This graph determined the coefficient of static friction.
static friction=.38
Part B:Kinetic Friction With Force Sensor:
What we did: We tied the sting from the brick and attached it to the force sensor. We then opened up logger pro and and recorded our data. in order to make this work we had to make the force on the force sensor be as close to constant as possible. We would pull on the sensor up untill the static friction broke. after it broke the friction reduced and we kept it as constant as possible. We took the recording of this information and it automatically graphed onto logger pro. In order to get a kinetic friction we took the data on the whole interval at which we tried to keep the force constant and got the average of it.
Apparatus Used: Force sensor
Part c:Static Friction from an angle to get it Sliding:
We Set up a ramp and placed the Blockk onto the ramp. We tried to get the angle at which the static friction broke. We gradually raised the ramp until the brick began to slide. The angle that made the block slide was 20 degrees. After taking several calculations and manipulating formulas we found that
Ms=Tan(theta)
Part D: Finding Kinetic Friction on a Ramp:
We used the same process as the one mentioned above, but this time solved for kinetic friction. The formula we obtained this time was
Mk=(mgsin(theta)-ma)/(mgCos(theta))
Mk=gsin(theta)/gcos(theta)
Part E: Finding acceleration with friction:
Motion sensor positioned at the top of the ramp.
We set up the ramp at a steeper angle and positioned the motion sensor on the top of the ramp. The Motion sensor sends a sound wave to determine the distance traveled during each time interval. Once again we recorded the block sliding down the ramp using logger pro and it automatically graphed our data. It made a velocity vs time graph. We got a linear fit on the data we needed and it gave us a formula. This formula was in the form Y=Mx+b Our M was valued at .8966. In conclusion Our acceleration is equal to .8966 since the derivative of this graph gives us our acceleration.
Acceleration=.8966
Conclusion: After following the instructions of lesson 7 ( Modeling Friction) we were able to come up with the formulas needed to find kinetic and static friction. This lab helped up visualize how to find kinetic and static friction and realize how it works. We were also able to find acceleration using logger pro.We were able to get familiar with two new apparatus the force sensor and the motion sensor. Once again we used logger pro and we are getting closer to proficiency with that cpu program.
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