physics help. conservation of momentum and conservation of energy?

Question

A man holding a gun ((mass of man)+(mass of gun)+(mass of bullet)=60kg)) skates on frictionless ice at an initial speed of +2 m/s and fires a 100 gram bullet with a speed of +500 m/s from the gun.

a) What is the speed of the man after firing the gun? (be sure to include +/- direction)

b) What is the initial total energy of the man-gun-bullet system (before the bullet is fired)? What is the final total energy of the man-gun-bullet system (just after the bullet is fired)?

c)is this an example of an elastic, inelastic, or perfectly inelastic collision, and why?

Answer 1

a) Using conservation of momentum
60*2=59.9*v+.1*500
solve for v, the speed of the man after firing the gun

v=1.17 m/s

b) energy before is
.5*60*4 J
120 J

after
.5*.1*500^2+.5*59.9*1.17^2 J
12541 J

c) This is inelastic
The additional energy came from the explosion of gunpowder that propelled the bullet.

j