It’s simpler than a jet engine, but clearly shows the action/reaction resulting from the high-speed expulsion of water. We like this resource because it’s a great way to visualize Newton’s Third Law. That’s roughly equivalent to 150 fire extinguishers. Instead, water is pumped out of the lake by the jetski at about 60 liters/second, then fired out the nozzles at 15 m/s, creating 1800N of force. It works on the same principle as a spacecraft being launched, but you don’t use rocket propellant to provide the thrust. This short video by physicist Derek Muller explores the physics behind jetpack rockets.
