- #1

MichaelKD

- 8

- 1

- Homework Statement
- A counterweight of mass m = 4.00 kg is attached to a light cord that is wound around a pulley. The pulley is a thin hoop of radius R = 8.00 cm and mass M = 2.00 kg. The spokes have negligible mass. (a) What is the magnitude of the net torque on the system about the axle of the pulley?

- Relevant Equations
- tau=I*alpha=Fr, F=ma

I started by summing the forces and torques to get:

- ma = mg-T

- I*alpha=Tr

I then used a=alpha*r and I=Mr^2 to combine the equations and solved for angular acceleration equals 81.75rad/s^2. Plugging this back into a torque equation I got that the net torque is 1.04Nm. However, the problem says the answer is 3.14Nm (which is my answer times 3. Does anyone know where I went wrong?

- ma = mg-T

- I*alpha=Tr

I then used a=alpha*r and I=Mr^2 to combine the equations and solved for angular acceleration equals 81.75rad/s^2. Plugging this back into a torque equation I got that the net torque is 1.04Nm. However, the problem says the answer is 3.14Nm (which is my answer times 3. Does anyone know where I went wrong?