An AC motor is a good example if I understand your question correctly.
When the motor is at rest and a sinusoidal waveform energizes it, the magnetic field has not yet been established and the windings appear as a short to the power source. At this stage there is, as of yet, no power transfer taking place between the power source and the load in the form of mechanical movement. Once the magnetic field establishes itself and the rotor begins to spin, power conversion takes place in inverse proportion. Current and torque goes down as motor speed goes up. The inertia of the rotor contributes to the reduction of necessary current to drive it.
Another way to look at this is to "measure" or take note of the force required to move a physical object that resists your efforts, then once the object's opposition is overcome the reduction of that force. For instance, imagine yourself breaking loose a very stiff bolt with a wrench. You exert a lot of force upon the bolt to get it to break free. Once it is broken free, it suddenly turns with ease and the force required to act upon it is reduced. Or consider another example. Think of the stationary automobile. Think about the torque that is required, and the demand put upon the motor, to get it in motion, but once in motion the inertia of the motion relieves the power required to keep it moving and thus a higher gear ratio with less torque can be used to keep it moving.