In an experiment, a torque of a known magnitude is exerted along the edge of a rotating disk. The disk rotates about its center. All frictional forces are considered to be negligible. Which of the following quantities should a student collect in order to determine the change in angular momentum of the disk for a specific time interval? Justify your selection. A) The initial angular velocity of the disk, because this quantity is related to the angular impulse of the disk.
B) The amount of time the torque is applied to the disk, because the time interval is related to the angular impulse of the disk.
C) The mass of the disk, because this quantity is related to the rotational inertia of the disk. The radius of the disk, because this quantity is related to the rotational inertia of the disk.

B) The amount of time the torque is applied to the disk, because the time interval is related to the angular impulse of the disk.

Explanation:

Angular impulse = Torque x time

= change in angular momentum

So,

Torque x time  = change in angular momentum

change in angular momentum = Torque x time

Torque is already known .

Hence to know the change in angular momentum what is needed to know is time duration of torque acting on the body .

An object did work on the environment.

Explanation:

If the work is done by the system on the environment then it is taken as positive but on the other hand, if work is done on the system by the environment then it is taken as negative.

Therefore when work done is positive then ,An object has been working on the environment.

Therefore the answer is  -

"An object did work on the environment."