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GMontey
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Homework Statement
Find an expression for the moment of inertia (I) of the platform in terms of acceleration of the mass (a), the value of the hanging mass (m), the radius of the spindle (r) and the constant (g).
Diagram: http://i.imgur.com/rv3zFYG.jpg
Homework Equations
F=ma t=Iα a=rα
The Attempt at a Solution
Net force: mg-T=ma (T is tension of spring)
Net torque: T-tf=Iα (T is tension of spring, tf is torque)
T=1/2ma
Apparently the answer is: I= (g/a-1)mr^2 but I'm having some trouble getting there.