Question

Hey

A gun of mass 5 kg fires A bullet of mass 20 g an itself recoils with a velocity of 0.25 metre per second. Find the velocity of the bullet in kilometre per hour.​

Answer 1

Mass of gun = 5kg

Mass of bullet = 20g or 0.02 kg

Initial velocity of bullet = 0

Initial velocity of gun = 0

Final velocity of gun = - 0.25 m/s

Now by using law of conservation of momentum :-

⇒ m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂

⇒ 5(0) + 0.02(0) = 5(- 0.25) + 0.02(v)

⇒ 0 + 0 = - 1.25 + 0.02(v)

⇒ 0 = - 1.25 + 0.02(v)

⇒ 0.02(v) = 1.25

⇒ v = 1.25 ÷ 0.02

⇒ v = 62.5 m/s

So velocity of bullet = 62.5 m/s

Or 62.5 × 18/5

⇒ 12.5 × 18

= 225 km/h

Answer 2

Solution:

Given:

➜ A gun of mass 5 kg fires A bullet of mass 20 g an itself recoils with a velocity of 0.25 metre per second.

Find:

➜ Find the velocity of the bullet in kilometre per hour.

According to the given:

➜ 5kg is the mass of the gun.

➜ 20 g is the mass of the bullet.

➜ 0 is the Initial velocity of bullet

➜ 0 is the Initial velocity of gun

➜ -0.25 m/s is final velocity of the gun.

Law of conservation of momentum:

➜ m₁ u₁ + m₂ u₂ = m₁ v₁ + m₂ v₂

➜ 5 (0) + 0.02 (0) = 5 (-0.25) + 0.02 (v)

➜ 0 + 0 = - 1.25 + 0.02 (v)

➜ 0 = - 1.25 + 0.02 (v)

➜ 0.02 (v) = 1.25

➜ v = 1.25 ÷ 0.02

➜ v = 62.5 m/s

62.5 m/s = velocity of bullet.

➜ 62.5 × 18/5

➜ 12.5 × 18

➜ 225 km/h

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