# Rotational motion

Problem 1

A wheel of radius 0.20 meters is mounted on a frictionless horizontal axis. The rotational inertia of the wheel about the axis is 0.050 kgm^2. A massless cord wrapped around the wheel is attached to a 2.0 kg block that slides on a horizontal frictionless surface. If a horizontal force of magnitude P=3.0 N is applied to the block as shown in the problem 1 attachment, what is the magnitude of the angular acceleration of the wheel? Assume the string does not slip on the wheel.

Problem 2

A 32.0 kg wheel, essentially, a thin hoop with radius 1.20 meters, is rotating a 280rev/min. It must be brought to a stop in 15.0 sec. How much work must be done to stop it? And what is the required average power?

https://brainmass.com/physics/rotation/rotational-motion-16461

#### Solution Preview

Hello and thank you for submitting your problem to BrainMass.

Please see the attached file.

<br>I solved problem 1 using two methods.

<br>The first method uses conservation of energy while the second method uses Newton's second law. Needless to say, the result is identical using both methods.

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<br>Before you look at the solution let ...

#### Solution Summary

The solution shows two approaches to the solve the problem and shows that the end result is the same.