A disk of mass M1 = 350 g and radius R1 = 10 cm rotates about its symmetry axis at finitial = 152 rpm. A second disk of mass M2 = 247 g and radius R2 = 5 cm, initially not rotating, is dropped on top of the first. Frictional forces act to bring the two disks to a common rotational speed f(final).(adsbygoogle = window.adsbygoogle || []).push({});

I already found f(final) to 129.2 rpm.

next the problem ask for the amount of Kinetic energy lost due to friction.

so i subtract initial KE from final KE to get the change in KE.

did i approach this wrong? b/c i kept getting the wrong answers....and all the numbers i got were pretty big...

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# Homework Help: Rotational collision

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