Average Velocity

The average velocity of an object is its total displacement divided by the total time taken. In other words, it is the rate at which an object changes its position from one place to another. Average velocity is a Vector quantity. The SI unit is meters per second. However, any distance unit per any time unit can be used when necessary, such as miles per hour (mph) or kilometer per hour (kmph).

How to calculate average velocity?

Calculating this velocity is a simple task. We just need to divide the total displacement by the total time elapsed:

\(\bar{v}=\frac{\Delta x}{\Delta t}=\frac{x_{f}-x_{0}}{t_{f}-t_{0}}\),

Average Velocity

Where, \(\Delta V\)  is the average velocity,

\(\Delta x\) is the displacement,

\(\Delta t\) is the total time,

\(^{x_{f}}\) and \(^{x_{0}}\) are the initial position and the final position,

\(^{t_{f}}\) and \(^{t_{0}}\) are the starting time and the ending time.

If we take the starting time to be zero, the formula becomes:

\(\bar{v}=\frac{\Delta x}{t}\)

Difference between Average Speed and Average Velocity:

There is often confusion over the difference between average speed and average velocity. In general usage, they are often substituted for each other. But in the world of Physics, speed and velocity are two distinctly different entities. Speed is a Scalar quantity whereas velocity is a Vector quantity. In effect, it means that speed does not require a direction but velocity needs direction.

It is enough to say that the speed of an object says, 25 m/s but on the other hand, the expression for the velocity of the same object will be 25 m/s, east (or any other direction). In the same vein, average speed and average velocity are direction unaware and direction aware respectively.

Average Velocity

For instance, if a remote controlled car is moving rapidly from Point A to Point B and back to Point A, there is no overall displacement of the car. In that case, the speed of the car can be measured but not its velocity. If the same car moves from Point A to Point B and stays there, there is definite displacement in a certain direction. It can be measured in such cases. In simpler words, average velocity is just the average speed with a direction.

Stay tuned with Byju’s to learn more about calculating average velocity and its relationship with speed with engaging video lectures.


Practise This Question

When a lift is going up, the potential energy of the person inside the lift remains the same as he is not gaining height with respect to the lift.