Got the right answer, just need an explanation with work shown. Thank you. On a

Question

Got the right answer, just need an explanation with work shown. Thank you.

On a digital video disc (DVD), video and audio data are stored in a series of tiny pits that are evenly spaced along a long spiral that spans most of the surface of the disc and extends from the inner edge of the DVD to the outer edge. The scanning laser in a DVD player reads this information at a constant rate. As the player reads information recorded closer and closer to the outer edge of the DVD, should the disc... rotate faster? Orotate slower? rotate at the same speed? Submit Your submissions: B Submitted: Tuesday, February 27 at 11:23 PM Feedback: Right answer!

Explanation / Answer

Using angular momentum conservation

L1 = L2

I1*w1 = I2*w2

for a disk moment of inertia is given by:

I = 0.5*M*R^2

0.5*M*R1^2*w1 = 0.5*M*R2^2*w2

w2/w1 = (R1/R2)^2

Now given that when player reads information than R is increasing, So

R1 < R2

Since angular velocity is inversely proportional to radius, So if R is increasing, than angular speed must be decreasing.

Which means rotate slower.

Please Upvote. Let me know if you have any doubts.

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