Question

. A marksman holds a rifle of mass mR = 3.50 kg loosely, so it can recoil freely. He fires a bullet of mass mB = 10 g horizontally with a velocity relative to the ground of vBx = 300 m/s. What is the recoil velocity vRx of the rifle? Find kinetic energy of the bullet and rifle right after firing and tell me which gets more kinetic energy

Answer 1

Answer:

bullet = 450 J

rifle = 1.3 J

So, the kinetic energy of bullet is much more than the kinetic energy of gun.

Explanation:

mass of rifle, mR = 3.50 kg

mass of bullet, mB = 10 g

velocity of bullet, vBx = 300 m/s

Let VG is the recoil velocity of gun.

By using the conservation of momentum

mass of gun x recoil velocity of gun = mass of bullet x velocity of bullet

3.50 x V = 0.01 x 300

V =  0.86 m/s

kinetic energy of bullet, KB = 0.5 x mB x vB²

KB = 0.5 x 0.01 x 300 x 300 = 450 J

kinetic energy of rifle, KG = 0.5 x mG x v²

KG = 0.5 x 3.5 x 0.86 x 0.86 = 1.3 J

So, the kinetic energy of bullet is much more than the kinetic energy of rifle.