Understanding how velocity is calculated is essential if you are to grasp the laws of physics. Learn the calculations necessary to figure it out.

### You will need

- Change in position
- Associated time

Step 1 Understand speed and velocity Recognize the difference between speed and velocity. Speed is the rate at which distance is changing. Velocity is the rate at which distance is changing and in what direction.

Step 2 Calculate speed Calculate speed. For example, if someone walked 20 feet east, 40 feet south, 20 feet west, and then 40 feet north in 400 seconds, the average speed would be 80 feet divided by 400 seconds, or 0.20 feet per second.

Step 3 Compare speed and velocity Calculate velocity. In the preceding example, the individual returns to the starting point. The average velocity is zero, even though the average speed was 0.2 feet per second.

An object moving away from and back to its starting point has zero velocity because the object always returns to its original position.

Step 4 Calculate velocity Specify the speed and change in position when calculating velocity. For example, if an airplane is traveling 300 miles per hour in a westward direction, its velocity would be 300 miles per hour, west.

Nikola Tesla was issued the first patent for a rotating-shaft speed indicator — or speedometer — in 1916.

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