A solid cylinder has a mass of 10kg and a radius of .2 meters. Starting from rest it achieves a rotational velocity of 2 revolutions per second after 4 seconds.(adsbygoogle = window.adsbygoogle || []).push({});

a. What torque is required to cause this?

I found the Inertia, (.5)(10(.2) =.2 and found alpha= 2*2pi/4 and got 3.142. Then I took

.2(3.142) to find the Torque of .628Nm.

The problem I encounter is on part b.

B. How long did it take for the cylinder to rotate through its first 2pi radians?

I think it sounds rather basic but the question confuses me. Am I suppose to use the radius of .2 and the 3.142. I really don't know what is wanting me to do.

And then for part c.

C. Assuming this is produced by a string wound around the cylinder, how hard in Newtons, would the string have to be pulled?

I use the Torque formula again right? F*L? so i take like .628 and divide it by .2 to get 3.14N?

Those are my thoughts, great appreciation to anyone who can help me out! Thanks!

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# Homework Help: A solid cylinder has a mass of

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