speed, change in distance with respect to time. Speed is a scalar rather than a vector 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.
The Columbia Electronic Encyclopedia, 6th ed. Copyright 2012, Columbia University Press. All rights reserved.
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