vis : Idioms & Phrases
Principle of vis viva
(Mech.) , the principle that the difference between the aggregate work of the accelerating forces of a system and that of the retarding forces is equal to one half the vis viva accumulated or lost in the system while the work is being done.
Webster 1913
Vis impressa
L. (Mech.) , force exerted, as in moving a body, or changing the direction of its motion; impressed force.
Webster 1913
Vis inertiæ
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L. (a) The resistance of matter, as when a body at rest is set in motion, or a body in motion is brought to rest, or has its motion changed, either in direction or in velocity.(b) Inertness; inactivity. Vis intertiæ and inertia are not strictly synonymous. The former implies the resistance itself which is given, while the latter implies merely the property by which it is given.
Webster 1913
Vis mortua
L. (Mech.) , dead force; force doing no active work, but only producing pressure.
Webster 1913
Vis vitæ , ∨ Vis vitalis
L. (Physiol.) , vital force.
Webster 1913
Vis viva
L. (Mech.) , living force; the force of a body moving against resistance, or doing work, in distinction from vis mortua, or dead force; the kinetic energy of a moving body; the capacity of a moving body to do work by reason of its being in motion. SeeKinetic energy , in the Note underEnergy . The term vis viva is not usually understood to include that part of the kinetic energy of the body which is due to the vibrations of its molecules.