Efficiency of a propeller is defined as the ratio of available power to the engine power which is. . (3). Note, that this definition for efficiency contains the velocity v, which means, that the efficiency approaches zero as the flight speed goes to zero, because the thrust cannot become infinitely large. So this definition is not useful for the special case of static thrust.
1 Compound Fracture: A compound fracture is a fracture in which the injured bone sticks through the skin. 2  Also known as an open fracture, a compound fracture can be a bit more serious in nature.
There is no difference between a bone break and a fracture. Fracture is the clinical term for a break in a bone. A fracture can range in severity from a hairline fracture, which is a small crack in the bone, to a compound fracture, which occurs when the broken bone punctures the skin.