Question

solid disk is spinning down from 220 rpm to rest. during this deceleration it does 2.5...

solid disk is spinning down from 220 rpm to rest. during this deceleration it does 2.5 kJ of work. What is its mass, it the radius of the disk is 0.8 m?

a. 16.2 kg

b. 22.6 kg

c. 29.5 kg

d. 8.25 kg

e. 4 kg

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Answer #1

The approach taken above is slightly length. A simpler and more direct way to do it is using work energy theorem which says that work done by external forces is change in kinetic energy of the system. Just find initial and final kinetic energy of the rotating disk, the difference will tell you the work done.

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