Question

a bullet having mass of 10gm and moving with speed 1.5m/s penetrates a wooden plank of 100gm. The bullet gets embedded in the plank and they both move.Find their velocity.​

Answer 1

ANSWER

mass of bullet=10g=0.01kg

velocity of bullet=1.5

s

m

mass of plank=90g=0.09kg

Total momentum before collision=mass of plank × velocity

=0.01×1.5+0.09×0=0.015kg

s

m

Total momentum after collision=(mass of bullet +mass of plank )× velocity

=0.1kg×V=0.1Vkg

s

m

According to law of conservation of momentum,

Total momentum before collision=Total momentum after collision

0.015kg

s

m

=0.1vkg

s

m

velocity acquired by the plank and the bullet=0.15

s

m

Answer 2

Given :-

☄ Mass of bullet, m₁ = 10g = 0.010 kg

☄ Mass of plank, m₂ = 90g = 0.090 kg

☄ Initial velocity of bullet, u₁ = 1.5 m/s

☄ Initial velocity of plank u₂ = 0 m/s

To find :-

The velocity (v₁ and v₂)

Solution :-

Let the finial Velocity of both bullet and plank be v ($\because$v₁ = v₂)

using the Law Of Conservation of momentum .i.e.,

➠ m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂

➠ (0.01)(1.5) + (0.09)(0) = (0.01)(v) + (0.09)(v)

➠ 0.015 + 0 = (0.01v + 0.09v)

➠ 0.015 = v(0.01 + 0.09)

➠ 0.015 = 0.1v

➠ v = 0.015/0.1

➠ v = 0.15 m/s

Thus, the plank moves with a velocity of 0.15 m/s.