Torque and Angular Acceleration

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SUMMARY

The discussion centers on calculating the angular acceleration of a pulley with a radius of 2.70 m and a moment of inertia of 39.0 kg∙m², subjected to a hanging mass of 4.20 kg. The force exerted by the mass is calculated as 41.16 N, resulting in a torque of 111.13 Nm. Participants emphasize the formula for net torque, which is the product of moment of inertia and angular acceleration, and seek clarification on additional components affecting net torque.

PREREQUISITES
  • Understanding of Newton's second law for rotation
  • Familiarity with torque calculations
  • Knowledge of moment of inertia concepts
  • Basic principles of angular motion
NEXT STEPS
  • Study the relationship between torque and angular acceleration in rotational dynamics
  • Explore the effects of friction and other forces on net torque
  • Learn how to calculate net torque in systems with multiple forces
  • Investigate the role of moment of inertia in different shapes and masses
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Physics students, mechanical engineers, and anyone interested in understanding rotational dynamics and torque calculations.

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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damnit I'm working on this same problem right now... having the SAME issue ><
 

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