<Moved from a technical forum. Therefore no template.> I am currently analysing the forces acting on a moving vehicle. The vehicle is mounted on a rail with wheels on both upper and lower side of the rail with a spring increasing the reaction force, and thereby the friction. The vehicle should be designed to reach an acceleration, a, of 9 m/s2. The vehicle have a mass, m, of 5 kg, and a cross-section area, A, of 0,04 m2. The wheel have a radius, r, of 0,106 m. Until now I have used the following equations: Fnet = Ft + Fd + Fr Where Fnet: Total longitudinal force required to reach the acceleration Ft = Traction force from the driving wheel Fd = drag force Fr = rolling resistance From this I get Fnet = 57,56 N Do I need to include the friction force in this equation? From this I have used two different formulas to calculate the Torque required to reach the needed acceleration: T = Fnet*r and T = I*alpha. Where I: moment of inertia of the wheel alpha: angular velocity I know the second equation is wrong, since only parameters for the driving wheel is included, but i have no idea how to use this for the whole vehicle. With the first equation I get a required torque of approximately 6,10 Nm. I do not believe this is correct, and I think I am missing out on something. I've been searching the forum for this problem, but I have not yet found an answer to this specific problem.