Getting up to speed

Add comment July 23rd, 2008

Webster’s says a “rate” is an “amount, degree, etc., of anything in relation to units of something else.” As one of its examples, it has “rate of speed per hour.”

I think “rate of speed” is redundant. Speed IS a rate, specifically, of distance (miles) per unit of time (hour). Therefore, it’s sufficient to say a car was traveling at “high speed,” not “a high rate of speed.”

In general usage, “velocity” is considered a synonym for “speed.” In the world of science, “velocity” includes speed and direction of motion. And the “rate of change” of velocity is “acceleration” (or “deceleration” if slowing).

Style footnote: The Associated Press says the abbreviation “mph” (no periods) is acceptable in ALL references to “miles per hour.”