Question
A bullet of mass 1 gm moving with a speed of 20m/s hits an ice block of mass 990 gm kept on a frictionless floor and gets tuck in it. the amount of ice that melts, if 50% of the lost kinetic energy goes to ice will be
(1) 0.030 g
(2) 0.30 g
(3) 0.0003 g
(4) 3.0 g
Joshi sir comment
amount of energy given by bullet = 0.5 (1/2) m v2 / 4.2 cal.
and amount of energy received by the ice block = ML here L is latent heat and M is mass of ice melted
on comparing we will get m v2/(4*4.2) = M*80 or M = 1*400/16.8*80 = 5/16.8 = 0.30 gm