Constant means "unchanging over time."

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​"Constant"

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Are speed and velocity the same thing?

NO!

Speed is the rate that a certain distance is covered over time.

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Speed is scalar.​ It tells us only the magnitude of how fast an object is moving.

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The SI unit for speed is meters per second (m/s)​

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Speed

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Velocity is the rate of displacement that is covered over time.

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Velocity is a vector.​ It tells us both the magnitude (speed) and direction of an object's motion.

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The SI unit for velocity is meters per second (m/s)​

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Velocity

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Constant speed and velocity

So if constant means "unchanging"...

Then constant speed or constant velocity means that an object's speed or velocity is not changing over time.

Any changes in an object's position over time can be graphed with position on the y-axis and time on the x-axis.

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​Position vs time graph

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The slope of a position vs time graph for an object experiencing constant motion is linear (a straight line).

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​Position vs time graph

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The slope of a linear graph can be calculated with rise over run.

Slope of an x-t graph

For a position vs time graph, the slope of the line represents the velocity of an object!

Slope of an x-t graph

Describing the Motion

Object is moving in a positive direction ​away from the origin with a constant positive velocity.

​Object is at rest at a positive position away from the origin.

​Object is moving in a negative direction towards the origin with a constant negative velocity.

Describing the Motion