How to Calculate the Average Velocity

Driving around a racetrack results in zero displacement.

Average velocity differs from average speed because velocity uses displacement instead of distance traveled. For example, if you did a lap around a 1-mile track, finishing where you started, your distance traveled would by 1 mile, but because you are at the same place you started, your displacement would be zero. Common units for average velocity are miles per hour (mph) and feet per second.

Things You'll Need

• Calculator

Instructions

1. Measure the displacement of the object you are calculating the average velocity using an appropriate measuring device to find the shortest distance between the starting and ending points. For example, if you are calculating displacement of an earthworm crawling across the ground, a ruler may be the best. If you are finding the average velocity of a car traveling cross-country, however, a map may be your best option.

2. Use a watch to determine the time elapsed between the start and finish.

3. Divide the total displacement by the time elapsed to calculate the average velocity. For example, if your car's displacement was 28 miles and it took two hours, you would divide 28 by 2 to get 14 mph.

References

• Dynamic Science: Motion - Average Velocity and Speed
• Physics Classroom: Speed and Velocity