Ok I'm in desperate need of some direction! I have the following question in which I must answer twice once using rotational dynamics and then again using Conservation of Mechanical Energy.(adsbygoogle = window.adsbygoogle || []).push({});

Question:

A massless string is wrapped around a solid cylinder as

shown in the diagram at the right. A block of mass

kg 2.0 = m hangs from the string. When released, the

block falls a distance 82 cm in 2.0 s. Starting with a freebody

diagram, calculate the mass of the cylinder.

I have started with ma + 0.5m(cylinder)a= -mg

That got me a mass of 43.2 kg for the cylinder

determining a from the equation v^2 = v2^2 +2a (y-y2)

a = 0.1025 m/s^2

But I don't think that's right

Now for Mechanical Energy I'm completely lost.

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