even more than before physics?

Question

An 845 kg dragster accelerates from rest to 100 km/h in .90 seconds.

What is the change in the momentum of the car?
What is the average force exerted on the car?
What exerts that force?

Answer 1

change in momentum = change in mv =
845 kg * 100 km/h = 845 N s^2/m * 100,000 m / 3600 s =
(84,500,000 / 3600) N s = 23,472.22 N s

F = m a
Avg. a = (100,000 m/3600 s) / 0.9 s
Avg. a = 30.86 m/s^2
F = m a = 845 kg * 30.86 m/s^2 = 26,080 kg m/s^2 = 26,080 N

What exerts the force?
Well, it depends on what is meant by the question.
I think the best answer is that it is the road surface that exerts the force.
If you stand in front of a wall and push against the wall, what exerts the force that pushes you backwards? Arguably, it is YOU that exerts the force. But I would say that the wall is pushing against your hand (i.e., it is resisting your push, resulting in a force in the direction that you are moving (backwards). By analogy, the road surface pushes the car forward at the same time that the car's tires are pushing backward against the road.

Answer 2

delta p = fnet delta t