PS-3220
Experiment 1: Rotational Inertia of a Point Mass
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013-15949A
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In the Properties window for Linear Accessory, select the size of the 3-step Pulley you are using. The default
setting is “Large Pulley (Groove)”. Click OK.
2.
Put a 50-g mass on the Mass Hanger and turn the 3-step Pulley to wind up the thread so the hanger is just
below the Super Pulley. Hold the 3-step Pulley.
3.
Click Record to begin recording data, and release the 3-step Pulley, allowing the hanger to fall.
4.
Caution! Click Stop to end data recording BEFORE the hanger reaches the floor or the thread completely
unwinds from the 3-step Pulley.
5.
In the Graph display, select the region of the data that represents when the Point Masses and Apparatus were
accelerating.
6.
In the display, select “Linear” from the curve fit menu.
The slope, m, of the linear fit represents the angular acceleration (a) for the Point Mass and Apparatus
7.
Record the value of the slope, m, as the angular acceleration in Data Table 2.
8.
Using calipers, measure the diameter of the pulley about which the thread is wrapped and calculate the radius.
Record the radius in Data Table 2.
In the previous procedure, the apparatus is rotating and contributing to the total rotational inertia. The next step is to
find the rotational inertia of the apparatus by itself so that this rotational inertia can be subtracted from the total.
