A magnetic tape is being played on a cassette deck. The tension in the tape applies a torque to the supply reel. Assuming the tension remains constant during playback, discuss how this torque varies as the reel becomes empty

A magnetic tape is being played on a cassette deck. The tension in the tape applies a torque to supply reel. Assuming the tension remains constant during playback, the torque varies as the reel becomes empty because the lever arm gets smaller. Therefore, the torque exerted on the reel by the tape becomes smaller.

Explanation:

Inertia increases and the angular momentum is to remain the constant.

Torque = rFsinФ

r=radius

F=force

Ф=angle between the F and lever arm