A string is wrapped around a uniform solid cylinder of radius r, as shown in the figure. The cylinder can rotate freely about its axis. The loose end of the string is attached to a block. The block and cylinder each have mass m.(adsbygoogle = window.adsbygoogle || []).push({});

http://session.masteringphysics.com/problemAsset/1011172/10/MAD_ia_6.jpg

Find the magnitude alpha of the angular acceleration of the cylinder as the block descends.

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I know that F=ma = -(T-mg) and

magnitude of torque that acts on pulley = I(alpha) = -Tr

and -T = 1/2 (m*r*alpha) if we substitute (0.5m(r^2)) which is the moment of inertia of a uniform cylinder in the second equation

and I also know that a = -alpha (r)

I guess I just don't see how i can use system of equations to eliminate T and still get an answer with variables r and g in the end ..

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# Homework Help: Acceleration of a pulley/ rotational kinematics - pleaaaase help

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