Question

a 10 kg bullet is shot froma a 5 kg gun with a velocity of 400ms-1 .what is the speed of recoil of the gun ?

Answer 1

Let speed of bullet be v1 , speed of recoil of gun is v2.
Mass of bullet be m1 and mass of gun be m2.
By conservation of linear momentum we have,
m1v1+m2v2=0

(10)(400)+(5)(v2)=0

v2=-(400)(10)/5

v2=-800m/s

Hence recoil speed of the gun is 800m/s.
Negative sign denotes opposite direction.