An automobile vehicle has a mass of 1500 kg. What must be the force between the vehicle and road if the vehicle is to be stopped with a negative acceleration of 1.7 m s^–2?

Mass of vehicle m = 1500kg

Retardation required a = −1.7ms⁻² 

Force between road and vehicle F= m x a =  1500×(−1.7) = − 2550 N

The force between the vehicle and road if the vehicle is to be stopped with a negative acceleration is friction force  which is − 2550 N.