Question

A car of mass 800 kg crashes into a brick wall at 8m/s. the car comes to a stop in just 0.1s. what force did the brick wall exert on the car to stop it that quickly? only enter the magnitude of the force in n (no minus signs). hint: use the relation between impulse and force, ∆p = f × ∆t

Answer 1

To find the force exerted by the brick wall on the car, the impulse-momentum theorem is applied. The initial momentum is calculated by multiplying the car's mass and velocity, and then the impulse is divided by the time interval to find the average force, which is 64000 N.

Step-by-step explanation:

To calculate the force that a brick wall exerted on an 800 kg car to stop it from a speed of 8 m/s in 0.1 s, we can use the impulse-momentum theorem. The impulse experienced by the car is equal to the change in momentum (Δp), which is the final momentum minus the initial momentum. In this case, the final momentum is zero because the car comes to a stop, and the initial momentum can be calculated by multiplying the mass of the car by its velocity. The formula for impulse (Δp) is given by the product of the average force (F) exerted and the time interval (Δt) over which the force is applied.

Δp = F × Δt

Let's calculate the impulse: Δp = mass × initial velocity = 800 kg × 8 m/s = 6400 kg·m/s.

Next, we use the impulse-momentum theorem to find the average exerted force:

F = Δp / Δt

F = 6400 kg·m/s / 0.1 s = 64000 N.

Therefore, the magnitude of the average force exerted by the brick wall on the car is 64000 N.