# speed

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Related to speed: Speed test

## speed,

change in distance with respect to time. Speed is a scalar rather than a vector**vector,**

quantity having both magnitude and direction; it may be represented by a directed line segment. Many physical quantities are vectors, e.g., force, velocity, and momentum.

**.....**Click the link for more information. quantity; i.e., the speed of a body tells one how fast the body is moving but not the direction of the motion. If during time

*t*a body travels over a distance

*s,*then the average speed of that body is equal to

*s/t.*The speed and direction of a body's motion together determine the body's velocity

**velocity,**

change in displacement with respect to time. Displacement is the vector counterpart of distance, having both magnitude and direction. Velocity is therefore also a vector quantity. The magnitude of velocity is known as the speed of a body.

**.....**Click the link for more information. .

## Speed

The time rate of change of position of a body without regard to direction. It is the numerical magnitude only of a velocity and hence is a scalar quantity. Linear speed is commonly measured in such units as meters per second, miles per hour, or feet per second.

Average linear speed is the ratio of the length of the path traversed by a body to the elapsed time during which the body moved through that path. Instantaneous speed is the limiting value of the foregoing ratio as the elapsed time approaches zero. *See* Velocity

## speed

[spēd] (graphic arts)

The sensitivity of a photographic film, expressed according to one of several scales.

(mechanics)

The time rate of change of position of a body without regard to direction; in other words, the magnitude of the velocity vector.

(optics)

The light-gathering power of a lens, expressed as the reciprocal of the

*f*number.The time that a camera shutter is open.

(physics)

In general, the rapidity with which a process takes place.

## Speed

an “illiterate loiterer”; slow-moving servant. [Br. Lit.:

*Two Gentlemen of Verona*]See: Laziness

## speed

**1.**

*Physics*

**a.**a scalar measure of the rate of movement of a body expressed either as the distance travelled divided by the time taken (

**average speed**) or the rate of change of position with respect to time at a particular point (

**instantaneous speed**). It is measured in metres per second, miles per hour, etc.

**b.**(not in technical usage) another word for velocity

**2.**a rate of rotation, usually expressed in revolutions per unit time

**3.**a gear ratio in a motor vehicle, bicycle, etc.

**4.**

*Photog*a numerical expression of the sensitivity to light of a particular type of film, paper, or plate

**5.**

*Photog*a measure of the ability of a lens to pass light from an object to the image position, determined by the aperture and also the transmitting power of the lens. It increases as the f-number is decreased and vice versa

**6.**a slang word for amphetamine

## SPEED

Early system on LGP-30. Listed in CACM 2(5):16 (May 1959).