Acceleration vs Velocity


Acceleration and velocity are frequently defined incorrectly and/or the relationship between them is misunderstood. Acceleration is defined as the rate at which an object changes its velocity. Velocity is defined as the rate at which an object changes its position. People regularly assume acceleration and velocity have a linear relationship of sorts. They think that if velocity is constant then acceleration must be constant, or that if acceleration is positive or negative it will be respectively speeding up or slowing down. It is also quite common to see the term speed (which is simply a distance over a time) confused for velocity, all the while forgetting that velocity (unlike speed) also has a direction. I spoke with a few friends of mine that graduated high school but were no longer involved in academia, asking them about acceleration and velocity to see what misconceptions they might have held. One of them gave an accurate definition of speed as well as the distorted speeding up theory for acceleration, but the most interesting part was his definition for velocity. He stated that velocity is "the force of the speed."

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The source of this misconception could come from a variety of places. The "accelerator" or gas pedal in a car likely furthers the false impression that acceleration causes an objects speed to increase. Velocity is a term that often flies under the radar of what people think they know. It's a term that nearly everyone has heard and yet, its true meaning is repeatedly mistaken to be the same as for speed. I suspect this arises because acceleration has already occupied the "speeding up" misinterpretation and because velocity is just speed with a direction, the direction is forgotten time and again sometimes rendering need to make up a new definition usually based on intuition rather than actual science.