With a stick, overcoming resistance can push an object. The speed at which an object moves depends on the speed at which the stick moves, because the stick is solid.

If a stream of water hits an object, it may also push an object. The larger the water volume and the higher the water flow velocity, the greater the driving force. The speed at which an object moves is different from the speed of water flow because water is a liquid and has no fixed shape.

If the water flow is open, there will be a great loss. If the water flow is collected in a container, the water will not be lost and the energy efficiency will be higher.
Because this technology mainly depends on the speed and quality of the liquid, that is, kinetic energy, it is called dynamic pressure transmission, or hydraulic transmission. Due to its flexibility, it also has certain applications, such as fluid couplings, torque converters, etc., but there are fewer product types and are not the subject of this book.
If you close the water and squeeze the stick, you can also push the object.