Torque and Angular Acceleration

AI Thread Summary
The discussion revolves around calculating the angular acceleration of a pulley with a radius of 2.70 m and a moment of inertia of 39.0 kg∙m², influenced by a hanging mass of 4.20 kg. The force exerted by the mass is calculated to be 41.16 N, leading to a torque of 111.13 Nm on the pulley. Participants express confusion regarding the net torque equation, specifically identifying additional components that may affect the calculation. Clarification is sought on how to account for these components to accurately determine the angular acceleration. Understanding the complete dynamics of the system is essential for solving the problem effectively.
r_swayze
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The pulley shown in the illustration has a radius of 2.70 m and a moment of inertia of 39.0 kg∙m2. The hanging mass is 4.20 kg and it exerts a force tangent to the edge of the pulley. What is the angular acceleration of the pulley?

All I have so far is the force exerted on the pulley by the block

mg = 4.2kg * 9.8m/s2 = 41.16N

which means it exerts a torque of r * F = 2.7m * 41.16N = 111.13Nm

I know net torque = moment of Inertia * angular acceleration, but I think I am missing another component of the net torque. What is that component and how do I find it?
 

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