magnitude of velocity of motion
This entry relates to the physical concept of speed; for the film, see Speed (1994 film)

Speed is the rate of motion, or equivalently the rate of change in position, often expressed as distance d traveled per unit of time t.


  • In Einstein’s corrected formula m has the value   where the “rest mass” m0 represents the mass of a body that is not moving and c is the speed of light, which is about 3×105 km⋅sec−1 or about 186,000 mi⋅sec−1.

    • Richard Feynman, The Feynman Lectures on Physics, Vol. I, Ch. 15. The Special Theory of Relativity
  • Be wise with speed;
    A fool at forty is a fool indeed.
  • Ares (The God of War) hates those who hesitate.
    • Heraclidæ (c 428 BC) line 722.
    • Euripides Alternate translation : Ares hates the sluggard most of all. (translated by David Kovacs)
  • It would be relevant … to point out the sinister part played by speed, by belief in speed as a value, by, in a word, a kind of impatience that has had a profound effect in changing even the very rhythms of the life of the spirit for the worse.
  • Ease and speed in doing a thing do not give the work lasting solidity or exactness of beauty.
  • Speed has never killed anyone. Suddenly becoming stationary, that's what gets you.
  • Speed is the essence of war. Take advantage of the enemy's unpreparedness; travel by unexpected routes and strike him where he has taken no precautions.

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