(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A 15 kg uniform disk of radius R = 0.25 m has a string wrapped around it, and a m = 5 kg weight is hanging on the string. The system of the weight and disk is released from rest.

a) When the 5 kg weight is moving with a speed of 1.7 m/s, what is the kinetic energy of the entire system?

2. Relevant equations

v=[tex]\omega[/tex]R

I=[tex]\Sigma[/tex](m)(r)^{2}

KE=(.5)(I)([tex]\omega[/tex])^{2}

KE_{total}= KE_{wheel}+ KE_{weight}

3. The attempt at a solution

KE(wheel) = (.5)((15)(.25)^{2})((1.7)/(.25))^{2}= 21.675

+

KE(weight) = (.5)(5)(1.7)^{2}= 7.225

= 28.9 [This answer is incorrect though, I'm unsure as to what I'm doing incorrectly.]

Any help is much appreciated, thanks! :)

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# Homework Help: KE of a rotational system

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