So the question is this:(adsbygoogle = window.adsbygoogle || []).push({});

A disc is released from rest. A block is causing it to rotate. After a time t the block has fallen a height h and the disc has rotated through an angle theta. (in rad)

Express h in terms of r (the radius of the part of the hub around which the string is wound) and theta.

I came up with this answer:

PE lost = KE gained

mgh = (1/2)mv^2 + (1/2)I(omega)^2

mgh = (1/2)m(r*omega)^2 + (1/2)*(mr^2)omega^2

gh = (1/2)r^2*omega^2 + (1/2)omega^2*r^2

gh = omega^2*r^2

omega = d(theta)/dt

subs for omega and solve for h: h = (r^2*theta^2)/(t^2*g)

The question asks me to express h in terms of r and theta but my answer has g and t in it. Any help?

Thanks in advance!

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# Rotational Physics

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