Question

A railway carriage of mass 9000 kg moving with a speed of 36 kmph collides with a stationary carriage of same mass. After the collision, the carriages get coupled and move together. What is their common speed after collision? What type of collision is this?

Answer 1

m₁ = 9000 kg, u₁ = 36 km/h = 10 m/s m₂ = 9000 kg, u₂ = 0, v = v₂ = v₂ = ? 

By conservation of momentum: m₁ u₁ + m₂ u₂ = (m₁ + m₂)v

∴ v = 5 m/s

As total K.E. after collision < Total K.E. before collision 

∴ collision is inelastic