A gun weighing 10 kg fires a bullet of 50gm with a velocity of 50m/sec. What is linear momentum of gun and bullet before and after firing?
total initial momentum=0
final momentum=final momentum of gun + final momentum of bullet
=mgvg + mbvb
=10*x+(50/1000)*500
=10x+25
BY PRINCIPLE OF CONSERVATON OF LINEAR MOMENTUM,
INITIAL MOMENTUM=FINAL MOMENTUM
0=10x+25
-25=10x
x=-2.5ms-1
the negative sign shows that the object is moving in opp. direction.
so, the gun recoils with the velocity of 2.5 ms-1.
The resultant momentum is 0 kgms-1 as the gun and bullet were at rest initially.