Question

When a passenger car collides head-on with a large 18-wheeler tractor trailer truck, the result can be catastrophic. Although the facts are rather grim, the analysis may well be eye-opening. Assuming a head-on highway collision in which the car and the truck stick together following the collision, estimate the changes in velocity by (a) the truck and (b) the car. (As usual, please state any of your assumptions and briefly explain how you arrive at your answers.)

Answer 1

a) since they are sticking together, the collision is completely inelastic. If we assume that both of the vehicles were moving with a constant velocity, the velocity of the truck after the collision would be in the same direction as it was before the collision, but it will be reduced. this is because the momentum of the car is less than that of the truck because of the higher mass of the truck. since this is an inelastic collision, a lot of kinetic energy is lost during the collision.

b) the car will move in the opposite direction to which it was originally moving, because it sticks to the truck and since the truck is heavier than the car and they are moving at the same speed (our assumption) the momentum of the truck is greater than the car's momentum. the final magnitude of the velocity would be lesser than the original magnitude due to loss of kinetic energy during the inelastic collision