where J is the total (moment of) inertia (i.e., of the motor itself and of the mechanical load), ωm is the angular mechanical rotor speed, τe is the electrical (driving) torque, and τl is the load torque. The dynamics are primarily determined by the inertia. If a constant nominal (rated) net torque τe − τl = τnom is applied at standstill, then the speed will increase linearly until nominal speed ωm = ωnom is reached after the open-loop rise time tro. The latter is proportional to the inertia as