The tape axis of the tape recorder rotates at a constant angular speed to rewind the tape. After rewinding, the end radius of the tape is three times the radius of the empty axis. The winding time is t, What's the difference between thick and thin tapes

The tape axis of the tape recorder rotates at a constant angular speed to rewind the tape. After rewinding, the end radius of the tape is three times the radius of the empty axis. The winding time is t, What's the difference between thick and thin tapes

Let's set the initial radius r, the final radius 3R, the thickness of the first tape D, the thickness of the second tape D / 2, the radius of the second tape R, the cross-sectional area of the first tape is s = pi * (3R) ^ 32 pi * (R) ^ 2 = 8pi * R ^ 2, so the length of the tape is L = s / D = 8pi * R ^ 2 / d