Energy

Converts energy between joules, kilojoules, megajoules, watt-hours, kilowatt-hours, and foot-pounds. Drone operators use it for battery energy and impact energy, and engineers for work and heat. Start with the energy converter. Pitfall: watts and watt-hours are different things. Watts are a rate, like speed; watt-hours are an amount, like distance. A battery holds watt-hours, a motor draws watts, and flight time is the first divided by the second.