Question

A van of mass 2000 kg travelling at 40 m/s dashes into a rear of a bus of mass 10.000 kg moving in the same direction at 5 m/s. The van bounces backward after the collision with a speed of 10m/s What was the velocity of the bus after impact?​

Answer 1

Given:

• mass of van (m₁) = 2000 kg
• mass of bus (m₂) = 10,000 kg
• Initial velocity of van (u₁) = 40 m/s
• Final velocity of van (v₁) = – 10 m/s (moves backward after collision)
• Initial velocity of bus (u₂) = 5 m/s

To Find:

• Final Velocity of the bus (v₂)

Concept To Be Applied: Use Law of Conservation Of Momentum.

• m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂

Calculation:

⇒ m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂

⇒ 2000 × 40 + 10,000 × 5 = 2000 × (– 10) + 10,000 × v₂

⇒ 80,000 + 50,000 = – 20,000 + 10,000 × v₂

⇒ 1,30,000 + 20,000 = 10,000 × v₂

⇒ 1,50,000 = 10,000 × v₂  

⇒ v₂ = 1,50,000 / 10,000

∴ v₂ = 15 m/s

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