A rope is wrapped around a wooden sylinder with I=2.9 and radius = 0.25m(adsbygoogle = window.adsbygoogle || []).push({});

A 50 kg crate is suspended to the free end of the rope and is pulled upwards with an acceleration of 0.80 m/s*s

A crank handle is attached to the axle of the wooden cylinder and when turned rotates about the axle in a circle of radius 0.12 m

What tangential force F applied tangentially to the rotating crank is required to raise the crate with the acceleration mentioned. Ignore the mass of the rope and I of axle and crank.

I did:

Total torque of the cylinder = FRh - McgRcy = Icy*A

(where Rh=radius of crank handle circle Mc=mass of crate Rcy= radius of cylinder I=moment of inertia of cylinder A=angular acceleration)

A= ay/Rcy (where ay = translational acceleration of the crate)

When I solve for F I get F=1098 N when I should get 1200. Could someone give me hint to what I'm doing wrong, please.

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# Homework Help: Rotational Dynamics of rope

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