Physics
Jet propulsion is most effective when the Reynolds number is high - that is, the object being propelled is relatively large and passing through a low-viscosity medium.
In biology, the most efficient jets are pulsed, rather than continuous: at least when the Reynolds number is greater than 6.
Read more about this topic: Jet Propulsion
Famous quotes containing the word physics:
“The fundamental laws of physics do not describe true facts about reality. Rendered as descriptions of facts, they are false; amended to be true, they lose their explanatory force.”
—Nancy Cartwright (b. 1945)