A student is asked to design an experiment to determine the change in angular momentum of a disk that rotates about its center and the product of the average torque applied to the disk and the time interval in which the torque is exerted. A net force is applied tangentially to the surface of the disk. The rotational inertia of the disk about its center is I = 1/2 MR^2 Which two of the following quantities should the student measure to determine the change in angular momentum of the disk after 10 s? Select two answers
A. The magnitude of the net force exerted on the disk
B. The distance between the center of the disk and where the net force is applied to the disk
C. The radius of the disk
D. The mass of the disk

A. The magnitude of the net force exerted on the disk

B. The distance between the center of the disk and where the net force is applied to the disk

Explanation:

To determine the change in angular momentum of the disk after a stipulated time, one must measure the above options.

The radius of the disk is fixed and does not vary with the experiment, and the mass of the disk is also constant and known.

One must first measure the magnitude of the net force exerted on the disk, and determine the torque as a result of this torque from the distance between the center of the disk and the point where the net force is applied.  The above statement also points out the necessity of measuring the distance between the center of the disk and the point where the net force is applied on the disk, as both the torque, and the moment of inertia is calculated from this point.

torque T = Force time distance of point of action of force from mid point of the disk

T = F X r

T x t = Δ(Iω)

Where t is the time,

and Δ(Iω) is change in angular momentum.

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