spool. Windup the string until the mass holder is just below the pulley. Press start and release the platen allowing the
apparatus to run through three oscillations then click stop. Using the mouse to place the cursor on the graph of angular
velocity, click and highlight the linear portion of the angular velocity graph. Under the fit option, select linear fit. The
slope of the linear fit is the angular acceleration (αP). Record this value on the data sheet. Next the student will repeat
this experiment for three different masses, 50gm, 70gms, 170 gms. Use a meter stick to measure radius(r) of platen,
record the value on the data page. Use the electronic scale to find the mass (M) of the platen and record the data on the
data page. Next, the students will find the formula for the moment of inertia of the disk using the necessary
measurements of the disk, calculate the moment of inertia of the disk (I). Using the values of the angular velocity ( of
the smart pulley, as determined from the graph of angular velocity. Calculate the angular acceleration (α) of the rotating
platen, using the formula, α=(P/r). Record theses values in the data table. Calculate the applied torque ( using your
value of the moment of inertia I and angular acceleration α. Next calculate the applied torque (from the equation m(g
Dα)D, as derived from the free body diagram. Then last the students will calculate the percent discrepancy between
and . For our personal experiment we started out with a 31% discrepancy at .025kg of suspended mass between torque
1 and torque 2 and after all the other trials we ended with a percent discrepancy of 12.5% and a suspended mass of .175
kg. Thus proving that as mass increases the percent discrepancy between the two applied torques will decrease.
Unfamiliar Terms
:
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•
Torque:
Torque, also called moment or moment of force, is the tendency of a force to rotate an
object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought
of as a twist. (
en.wikipedia.org/wiki/Torque
)
•
Vernier caliper
:
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 Fall '11
 BrunoBauer
 Physics, Angular Momentum, Force, Mass, Moment Of Inertia, Rotation, Angular Acceleration, percent discrepancy

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