Question

Two vehicles collide head on, and are brought to a complete standstill by the collision. The first vehicle had a mass of 450 kg and was travelling at 16 m/s before the collision. The second had a mass of 400 kg. What was its speed before the collision?

Answer 1

Answer: 2.24 m/s

Step-by-step explanation:

Let's use kinetic energy equations to solve this problem:

The kinetic energy of the first vehicle before the collision is:

Ek=½mv^2 = ½ * 450 kg * 16 m/s^2 = 4,800 J

The kinetic energy of the second vehicle is equal to that of the first, because the collision has made them come to a complete standstill:

Ek = ½mv^2 = ½ * 400 kg * v^2 = 4,800 J

From this, we get that:

v = sqrt(4,800 J / 400 kg) = sqrt(4.8) m/s = 2.24 m/s

So the second vehicle was travelling at 2.24 m/s before the collision.