A Disc-Shaped Grindstone of Mass 3 $\times$ 10^-3 J
C)4 $\times$ 10^-5 J
D)1

Multiple Choice

A disc-shaped grindstone of mass 3.0 kg and radius 8.0 cm is spinning at 600 rev/min.After the power is shut off,a man continues to sharpen his axe by holding it against the grindstone until it stops 10 s later.What was the stone's initial kinetic energy when the power was turned off?

A) 19 J
B) 3.8 $\times$ 10^-3 J
C) 4.8 $\times$ 10^-5 J
D) 1.9 $\times$ 10^-3 J
E) 2.4 $\times$ 10^-2 J