Dennis:
I get the feeling that that's a homework problem, so I don't think I'll answer it as such.
But I'll try to hint at the answer.
If velocity is constant, that means that there is no acceleration
(by definition). So if there is no acceleration, there is no net force
acting on the car.
If there is a force pushing the car forward, you'd see its velocity
increase because it would accelerate, from Newton's Second Law. If
friction were greater than the applied force, the car would also slow
down due to the force of friction. What happens if the force of
friction equals the pushing force on the car, that makes it go forward?
Think of that and remember that F = ma, and I think you might find the answer.
Jason
(published on 10/22/2007)
