What net force increases a velocity of a car from 20 m/s to 35 m/s in 8.0 s if the mass of the car is 1600 kg? (3000 N). What force would cause the car to stop? (3000N) What coefficient of friction is needed to supply the force of friction? (.0191)
are they correct?
The first is correct. The second , the force to stop is any Net force will cause it to stop. If it has friction, friction will cause it to stop. Now if the pushing force is still applied, then you need a force >3000N to stop the car.
So the third answer depends on the second.
Pushing force-frictionforce= m(15/8) =netforce
so you are right on that first part.
The second, and third, cannot be answered without some assumptions, and the answers will vary.