Difference Between Speed And Velocity

What's the difference between speed and velocity?

Speed is how fast an object is moving, while velocity is the rate at which an object changes position in a certain direction. Speed is calculated by the displacement of space per a unit of time. Velocity is calculated by the displacement of space per a unit of time in a certain direction. In short, velocity factors in direction, but speed does not.

Expert Answers

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Sometimes it helps to have a visual representation:

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The short answer is that velocity is the speed with a direction, while speed does not have a direction.

Speed is a scalar quantity—it is the magnitude of the velocity. Speed is measured in units of distance divided by time (e.g., miles per hour, feet per second, meters per second, etc.).

Velocity is a vector quantity—when giving the velocity we must specify the magnitude (the speed) and the direction of travel. For example you might drive 100km/hr (the speed) in a northerly direction.

This is analogous to the difference between distance (a scalar quantity) and displacement (the distance with direction).

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This is a great question and I can see your confusion. There are similarities, but there are also differences. I will give you a definition of each and then provide an example.

Speed refers to how fast an object is moving. It is calculated by the displacement of space per a unit of time.

Velocity refer to the rate at which an object changes position in a certain direction. It is calculated by the displacement of space per a unit of time in a certain direction.

These definition might sound the same, but there is a crucial difference. It deals with direction. Velocity deals with direction and speed does not. Let me give you an example.

If you were driving at 50 miles per hour to get to a store, you would say that your speed is 50 miles per hours. If you were driving in a circle and ended at the same place, you would say that your velocity is zero, because there was no directional gain. The key to remember is that velocity is a vector, which means there is a directional component.

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