Velocity versus Speed: Are they the same?

Velocity and speed are not the same in physics.  Let’s begin with the definition of velocity and then we will see how velocity compares with speed.  The velocity of an object is determined by how far an object travels in a certain direction within a certain period of time.  In other words, average velocity is equal to the change in position over the change in time, as illustrated in the following mathematical equation:


Speed is defined as the distance an object travels during a certain time period.  At first glance, the definitions for both velocity and speed appear to be the same.  Both quantities have a measurement of distance in the numerator and a change in time in the denominator.  The difference between velocity and speed is that velocity takes into account direction and distance whereas speed is calculated without direction.

Velocity is a vector.  It has both a magnitude (how large of a distance traveled) as well as a direction (north, south, positive, negative).  Speed on the other hand, is not a vector as it is just associated with a magnitude and not a direction.  Because velocity is associated with a direction, it can be positive or negative, whereas speed will always have a positive value.

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