With rolling resistance and air resistance

More realistically, however, we would expect there to be non-conservative forces acting on the trike, such as rolling resistance and aerodynamic drag. When these forces act upon the trike a simple analytical solution becomes less easy to obtain, at least if the angle of descent is allowed to not remain constant. To parametize the problem we will use an independent variable $s$ that will be distance, in metres, from the summit of the hill or mountain. We will assume this mountain has a road that we are travelling down and $s$ is the distance from the summit along this road.