## Main Difference – Average Speed vs. Average Velocity

**Average speed** and **average velocity** are both measurements of rate of change of position in a body. The **main difference** between average speed and average velocity is that the *average speed is calculated as the total distance traveled by a body divided by the time taken*, while *average velocity is the displacement divided by the time taken*. Both quantities have **units ms ^{-1}**. For an object moving in a straight line, the magnitude of average velocity is equal to the body’s average speed.

## What is Average Speed

Average speed of a body is the total distance traveled by a body divided by the time taken. **distance** is a measurement of the total path length traveled by an object. Distance is a scalar quantity (it has no specific direction). Hence average speed is also a scalar quantity.

## What is Average Velocity

Average velocity is the displacement divided by the time taken. **Displacement** measures the shortest distance between the object’s initial position and its final position. It is a **vector** quantity with the direction of the vector being the direction from the starting point to the final point. Since *displacement* is a vector quantity, average velocity is also a vector quantity.

The diagram below shows the difference between *distance* and *displacement*:

## Difference Between Average Speed and Average Velocity – An Example

An Olympic track has a circumference of 400 m. The World Record for women’s 400 m sprint was set in 1985 by Marita Koch of (what was then) East Germany. If her record was a time of 47.60 s, find,

a) her average speed

b) her average velocity

for her record-setting 400 m sprint.

a) Her average speed is simply the total distance (400 m) divided by the total time (47.60 s)

b) 400 m include one *complete round *around the track. In the end, Marita needs to come back to the starting point to finish the race. This means that her *displacement is 0*.

## Difference Between Average Speed and Average Velocity

### Definition of Average Speed and Average Velocity

**Average speed** is the total distance traveled divided by the time. Speed takes into account the total path length traveled.

**Average velocity **is the displacement divided by the time. Velocity only takes into account the starting and ending points of an object’s path.

### Direction

**Average speed **has no specific direction. It is a scalar quantity.

**Average velocity** has a specified direction. It is a vector quantity.