Trade-offs and energy conservation

You have a choice for doing many jobs. You choose your trade-off.

Sharing a load using pulleys

Pulleys help to lift loads. The trade-off is between a large force or a large distance.

Other devices (levers, ramps, bicycles) can be used to lift, or drag, but it's always a trade-off between force and distance.

choices in circuits

You can choose different electrical circuits to do many jobs. There is always a trade-off between current and voltage.

If you use a circuit to light a lamp, here is the trade-off.