Question

A large truck and a car, both moving with a velocity of magnitude v, have a head-on collision and both of them come to a halt after that. If the collision lasts for 1 s:
(a) Which vehicle experiences the greater force of impact?
(b) Which vehicle experiences the greater change in momentum?
(c) Which vehicle experiences the greater acceleration?
(d) Why is the car likely to suffer more damage than the truck?

Answer 1

Let the mass of truck = M, Velocity of car = - v time for which collision lasts, t = 1 s
(a) On collision, both the vehicles experience the same force, as action and reaction are equal.
(b) Change in the momentum of the truck is equal and opposite to change in momentum of the car, i.e, both the vehicles experience the same change in momentum.
(c) As acceleration $=\frac{force}{mass}$, and force on each vehicle is same, acceleration $\propto \frac{1}{mass}$. As the mass of the car is smaller, therefore, acceleration of the car is greater than the acceleration of the truck.
(d) The car is likely to suffer more damage than the truck, as is is lighter. The acceleration, i.e., change in velocity of the car is more than that of the truck.