A gun of mass M fires a bullet of mass m with a velocity v relative to the gun. The average force required to bring the gun to rest in 1 sec is

F=mMv(M+m)t  =mMv1(M+m) Assume that velocity of the bullet is v2   and velocity of the gun is v1then  M V1=m V2.........1 GIVEN   VREL=v=V2+V1.........2 force required to hold the gun =F=M V1t  given t=1 F=M V1.........3 FROM  1,2 and 3 F= M m vM+m