Velocity of bullet + ice block, V=(10 gm)×(20m/s)1000 gm=0.2 m/s
Loss of K.E.=12mv2−12(m+M)V2
=12[0.01×(20)2−1×(0.2)2]=1.98 J
∴ Heat generated =1.984.2cal.
∴ Heat received by ice block =1.984.2×2cal=0.24 cal.
∴ Mass of ice melted =(0.24cal)(80 cal/gm)=0.003 gm.