Question

An 18 000-kg freight car travelling 1.75 m/s[E] collides with a 27 000-kg freight car at rest. After the collision, the freight cars stick together. What is the velocity of the freight cars after the collision?

Answer 1

Answer:

The velocity of the freight cars after collision is 0.7 m/s

Explanation:

Given;

mass of the first freight car, m₁ = 18000 kg

initial speed of the first freight car, u₁ = 1.75 m/s

mass of the second freight car, m₂ = 27000 kg

initial speed of the second freight car, u₂ = 0

Let the velocity of the freight cars after collision = v

Apply the principle of conservation of linear momentum;

m₁u₁ + m₂u₂ = v(m₁ + m₂)

18000(1.75) + 27000(0) = v(18000 + 27000)

31500 = 45000v

v = 31500 / 45000

v = 0.7 m/s

Therefore, the velocity of the freight cars after collision is 0.7 m/s