course Phy 231
I reviewed my work with the angular velocity lab. The values I entered in the discussion form as 'dv/ clock time were incorrect. I have calculated the 'dv / clock time that I thought I had done, though it will not give the acceleration, to see how the results compared to the correct calculation. In neither one did I see a constant change in acceleration. I believe the change in acceleration should be constant, but my data doesn't reflect this.I also noticed a transposition error in two of my interval times. The second revolution is actually faster than the first.
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I repeated the exercise using another interval, but I still don't see a constant acceleration." "This trial resulted in 670? of rotation in 5.14 seconds. The strap ended with an angle of 130? from the start point. It passed the start point at the following clock times in seconds:
.6875, 1.046875, 1.234275
It came to rest at approximately 130? from the start point at 2.171875 seconds.
The velocity in degrees per second for each interval:
180?/.6975 sec = 261?/sec
180?/1.046875 sec = 171?/sec
180?/1.234275 sec = 145?/sec
130?/2.171875 sec = 60?/sec
The change in velocity for each interval:
261?/sec (change from zero)
-90?/sec
-26?/sec
-85?/sec
The acceleration calculated as the change in velocity divided by the change in time:
379?/sec^2
-86?/sec^2
-21?/sec^2
-39?/sec^2
Considering only the decreasing velocities, the acceleration does not appear to be changing at a constant rate."
Good. Acceleration due to friction does tend to be a bit sporadic, and combined with experimental uncertainties it is difficult to confirm a hypothesis that acceleration is constant.