# Rotation: Moment of inertia and angular velocity.

(See attached file for full problem description with diagram and symbols)

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1.) A thin, 80.0 disk with a diameter of 9.00 rotates about an axis through its center with 0.220 of kinetic energy.

What is the speed of a point on the rim?

2.) A 3.0-m-long rigid beam with a mass of 100 kg is supported at each end. An 80 kg student stands 2.0 m from support 1. How much upward force does support 1 exert on the beam?

3.) The 20-cm-diameter disk in the figure can rotate on an axle through its center.

What is the net torque about the axle? In Nm

4.) A 1.0 kg ball and a 2.0 kg ball are connected by a 1.0-m-long rigid, massless rod. The rod is rotating cw about its center of mass at 20 rpm.

What torque will bring the balls to a halt in 5.0 s? in Nm

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https://brainmass.com/physics/velocity/rotation-moment-of-inertia-and-angular-velocity-54849

#### Solution Summary

Four problems related to rotational motion are solved.