Question

If a 1500 kg car is moving at 20 m/s and hits a brick wall and you know that it comes to rest in 0.80 s then how much force does the car sustain

Answer 1

consider the direction towards the wall as negative  and away from the wall as positive.

m = mass of the car colliding with the brick wall = 1500 kg

v₀ = initial velocity of the car towards the wall = - 20 m/s

v = final velocity of the car = 0 m/s

t = time taken by car to come to rest after collision = 0.80 s

F = force sustained by the car

using impulse-change in momentum

F t = m (v - v₀ )

inserting the values

F (0.80) = (1500) (0 - (- 20))

F (0.80) = 30,000

F = 30000/0.80

F = 37500 N