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course PHY 201
5/2 about 1:46 pm
I viewed this experiment and it allowed me to answer the first question of Query 31.Experiment 29. When a weight attached by a thread around the horizontal axle of a rotating disk falls, the average velocity of the falling weight is proportional to the average angular velocity of the disk.
Associated video clip is on the CD EPS02.
By moving the weight a known distance and measuring the resulting angular displacement of the disk, the ratio of the linear distance to the angular distance can be determined. The ratio of the distance moved by of a point on the disk to the distance moved by the weight can also be seen to be equal to the ratio of the distance of the point from the axle and the radius of the axle.
By measuring the time required for the weight to descend from rest to different distances below its initial point, it can be determined that the acceleration of the weight is approximately uniform. It can then be inferred that the acceleration of the disk is approximately uniform, and that the average velocity of the weight is therefore equal to the average of its initial and file velocities, with a similar relationship for angular velocities of the disk.
The proportionality constant between the inferred average velocities of the weight and average angular velocities of the disk can then be related to the radius of the axle.
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Very good.
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