A bullet of mass 0.01kg is fired with velocity of 0m/s in to a sack of sand of mass 9.99kg which is swinging from rope. At the moment the bullet hits, the sack has a velocity of 0.2m/s. Workout the velocity of bullet and sand just after the bullet hits the sack

Answer 1

The velocity of the bullet and the sand just after the bullet hits the sack can be calculated using the conservation of momentum.

Momentum of bullet before impact = 0 kg m/s
Momentum of sand before impact = 9.99 kg x 0.2 m/s = 1.998 kg m/s

Momentum of bullet + sand after impact = 0 kg m/s

Therefore, the momentum of the bullet after impact = -1.998 kg m/s

The velocity of the bullet after impact = -1.998 kg m/s / 0.01 kg = -199.8 m/s

The velocity of the sand after impact = 1.998 kg m/s / 9.99 kg = 0.2 m/s

Answer 2

Oh come on, the bullet is in the sand !