Question

The bag of sand of mass 2 kg is suspended by a rope. A bullet of mass 10 g is fired at it and gets embedded into it. The bag rises up a vertical height of 10 cm. The initial velocity of the bullet is nearly

Answer 1

Answer:

1. energy should be conserved in this case so gain in potential energy =loss in kinetic energy

Answer 2

Answer:

vь ≈280 m/s

Explanation:

Given :  

m1=2kg        

m2=0.01kg            

h=10cm

h=0.1 m

Let the initial speed of the bullet be vb.

From energy conservation :     (m₁+m₂)  gh = 1/2(m₁+m₂)V²

⟹ V=√2gh

  V=√2×9.8×0.1 =1.4 m/s

Momentum conservation :     m₂vь=(m₁+m₂)V

∴0.01 vь=(2+0.01)×1.4

⟹  vь ≈280 m/s