# We are going to use this to make a crude estimate of

• Lab Report
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We are going to use this to make a crude estimate of the frictional torque of the bearings. 4.) Remove the 5 gram pan. Take the 50 gram mass pan and use the masking tape to tape a 40 gram rider onto the pan. Place this “mass grouping” onto a scale and measure the total mass. Record this value on the data sheet as mass m . This should be enough to do all of the experiment. Next, tie mass m onto the nylon string. Do a test run by releasing the pan. This mass should get the system to accelerate smoothly . You need to be able to perform this process consistently. Now, determine a fixed vertical distance from the floor to the bottom of the pan at that point from which it is to be released. (I recommend one meter .) Record the value of on the data sheet. Do a few more test runs and use the stopwatch to time the pan from release to the instant it strikes the floor. It is advisable to put something “soft” on the floor, under the pan to cushion it when it strikes the floor. 5.) Do five official runs and record your times on the data sheet. 6.) Average your five times and record this value on the data sheet. 7.) Calculate I D , the moment of inertia of the Rotodyne wheel, using equation (11). I D = mR 2 1 m f m gt ave 2 2 1 . (11) Measuring the Moment of Inertia of the Wheel with Four Cylindrical Masses Attached (Configuration One) cylindrical masses 2 d 1 8.) There are four sets of five holes on the Rotodyne wheel platform. For configuration one, we 9-6
are going to use hole three counting outward from the center, as represented in the diagram above. Screw a 250 gram cylindrical masse into each of the four holes shown. To measure the value of d 1 , the distance from the center of the wheel to the center of the cylinder, it is probably easiest to measure from the center of one cylinder to the center of the opposite cylinder and divide the value by two. Record the value of your measurement on the data sheet. 9.) Using the Vernier calipers, measure D the diameter of a cylindrical mass and record this value on the data sheet. 10.) Still using hanging mass m , do five official runs and record your times on the data sheet. 11.) Calculate the average of your five times and record this value on the data sheet. 12.) Again, use equation (11) to “measure” the total moment of inertia I tot, 1 of this system. Measuring the Moment of Inertia of the Wheel with Four Cylindrical Masses (Configuration Two) cylindrical masses 2 d 2 13.) Screw the four 250 gram cylindrical masses into the four holes farthest from the hub of the wheel; hole five. Measure the value of d 2 , the distance from the center of the wheel to the center of a cylinder. 14.) Using hanging mass m , do five official runs and record your times on the data sheet. 15.) Average your five times and record this value on the data sheet.