Final answer:
The force that caused the change in momentum of a car is calculated using the formula F = Δp / Δt, resulting in a force of 800 N.
Step-by-step explanation:
The question is asking us to calculate the size of the force that caused a change in momentum of a car. To find the force, we use the formula derived from Newton's second law of motion, which is force equals the change in momentum (impulse) divided by the time over which it occurs, F = Δp / Δt.
In this case, the change in momentum (Δp) is 4000 kg·m/s and the time (Δt) is 5 seconds. Using the formula: F = 4000 kg·m/s / 5 s = 800 N, we find that the size of the force is 800 newtons. So the correct answer is (c) 800 N.