Forces on the road
For any car travelling at a CONSTANT VELOCITY, the resultant force on it is zero.
Why? because the driving force of its ENGINE (which is making the car go forward) is BALANCED by the RESISTIVE FORCES, like friction and air resistance. (which tend to force the car to go backwards).
the BRAKING FORCE needed to stop a vehicle in a certain distance depends on:
- speed of the vehicle when the brakes are first applied
- the mass of the vehicle
and to see this…