A car is abruptly stopped by hitting a crash reduction barrier. It was traveling at a speed of 30 m/s when it hit the barrier, and the time that it took to stop was 0.5 ms

Question

A car is abruptly stopped by hitting a crash reduction barrier. It was traveling at a speed of 30

m/s when it hit the barrier, and the time that it took to stop was 0.5 ms. What was the force on

the car if it has a mass of 2500 Kg?

Answer 1

To solve this problem, we can use momentum and impulse. The momentum of the car can be found with its mass and velocity. The momentum is mv = (2500kg)(30m/s) = 75000kgm/s. Once the car stops, its momentum is 0 since v = 0. The change in momentum is the impulse acted upon it by the barrier, which is 75000kgm/s in this case. However, we also know that impulse is equal to Ft (force times time), so Ft = 75000kgm/s. Now since t = 0.5 ms = 0.5 * 10^-3s, F = (75000kgm/s)/(0.5 * 10^-3s) = 1.5 * 10⁸N, which is our answer since it is the average force acted upon the car.