Question

a bullet leaves a eifle with a velocity of 100 M per second and the rifle of mass 2.5 kg recoils with the velocity of 1 metre per second. find the mass of the bullet

Answer 1

By using the conservation of momentum theorem-
Mass of bullet*initial velocity of bullet+Mass of gun*intial velocity of gun=Mass of Bullet*final velocity of bullet+Mass of Gun*final velocity of gun, So:
M1U1+M2U2=M1V1+M2V2
And initial velocity of both the gun and bullet is 0
So
0=M1V1+M2V2
M1V1=-M2V2
Now puttting values(M1 and V1 are mass and velocity of bullet and M2 and V2 are mass and velocity of gun respectively)
100*M1=2.5*1
M1=2.5/100
M1=0.025kg
Or
M1=25 grams