Hi, I'm working on a mythical gadget for an sf novel that converts electrical power into acceleration. I'm having a hard time figuring out this relationship from my science references. I suspect I've forgot some calculus that might be required. I'd like to figure out the real relationship between Netwons and Watt-hrs of electricity so I can make a statement like "at 100% efficiency, the gadget would consume x Watt-hrs of electric power and produce y Netwons of force each hour." Can someone give me a formula?