1. The problem statement, all variables and given/known data The vehicle now accelerates to a constant speed of 55 m s–1. The useful power output of the motors is 22 kW at this speed. Calculate the horizontal resistive force acting on the vehicle? 2. Relevant equations P=FV 3. The attempt at a solution: F=P/V so the answer is 400N But what I do not understand is why are we using that formula and how do we know that is the resistive force?