For the first setup, we wanted to measure the static friction coefficient between a block with a felt surface and the table top of our desk. To get the most accurate value of a static friction coefficient, we attached a string to the block, hung it over a pulley and attached a cup to the other end so we could slowly add water and find the hanging weight that would finally overcome static friction (setup below). We weighed and found the masses for the block with felt and the cup with enough water to make the block start moving. We then added another block and more water to repeat the process. We repeated this until we had four blocks in total being dragged and recorded the mass of the water each time we added a block (table below). We then graphed our data in Logger Pro and found that the values are proportional to each other by a multiple which happens to be our static coefficient (graph below). As seen in the graph, the coefficient of static friction for Part 1 is 0.183.
I calculated the coefficient of static friction myself and found that I got different values for each trial (seen below). I think we weren't as careful as we could be when adding water to the cup.
Part 2 of the lab dealt with kinetic friction. This time, we used a force sensor when we took data (seen below). In order to use the sensor we had to calibrate it which required us to hang 500g from the little hook it has and then set it on its side and zero the sensor. We then attached the wooden block we were using before with a string to the sensor and pulled at a constant speed while collecting data. We repeated this process until we were pulling the same four blocks in total.
We then stored each run for its data and graphed the values to get a kinetic friction coefficient of 0.232 (seen below).
For Part 3, we measured static friction on a sloped surface (setup below). For this part, we raised a track with the felt surface block on it with one of our phones on it to measure the angle at which the block starts to slip. This was the 0.1307kg block and it started to slip at an angle of 14 degrees.
With a simple calculation with force diagrams, we were able to obtain the coefficient of static friction (seen below).
Part 4 of our lab required that we use a motion detector attached to our track at the top to measure the acceleration of the block as it slides down (setup below). We also measured the angle it was sliding at with our phone.
Seen below is the graph of our block sliding down the track.
The slope of our velocity graph here is our acceleration, a=1.854m/s^2, which we use to calculate the coefficient of kinetic friction.
Part 5 of the lab has us use our coefficient of kinetic friction from Part 4 to find the acceleration of the block if it was attached to a hanging mass that is "sufficiently heavy". We were to first create a model and a prediction for what the acceleration would be (seen below). Here we set our hanging mass to a value of 0.05kg and got a=0.835m/s^2.
We then hung a 0.05kg mass to the felt block over a pulley and used a motion sensor to track the block. Below is our findings with acceleration being listed as 0.5571m/s^2. Our value is kinda off because factors outside of an ideal situation which is assumed in our prediction could have taken place. Maybe the block skipped or we didn't have the string parallel to the ground when the hanging mass fell or there might have been left over tape on the track.
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