Question

If the vehicle is running on the road having 10% gradient at a constant speed, then on flat road it will accelerate at approximately 1 m/s2 (All the parameters remain the same).

(a) True

(b) False

I got this question in an international level competition.

The origin of the question is Vehicles and Powertrain topic in portion Emission Control Methods, Electric & Conventional Vehicles of Automobile Engineering

Answer 1

The correct answer is (a) True

The explanation is: F net = Ftraction – Frolling – Faerodynamic – Fgradient. In case 1: Due to constant speed ⇒ avehicle = 0 ⇒ Fnet = 0 N and Ftraction = Frolling + Faerodynamic + F gradient. In case 2: Due to flat road, Fgradient = 0 N and Fnet = Ftraction – Frolling – Faerodynamic. As all parameter remain the same ⇒ Ftraction will be the same. Therefore Fnet = Fgradient. Fnet = mvehicle * avehicle = mvehicle * g * sin (α) = Fgrad. For small values, sin (α) = α. Therefore avehicle = g * α = 9.81 * 0.1 = 0.981 m/s^2 which is approximately 1 m/s^2.