The rate of change of velocity with time is called acceleration. In the previous lesson we have already studied acceleration in detail. in this lesson we are going to learn what is average acceleration and what is average acceleration formula with some basic questions.

What do you mean by average? An average can be defined as the number you get when you two or more figures together and then divide the total by the number of figures you added. By Similar way the average acceleration will be calculated.

## Average Acceleration Definition

Average acceleration is defined as the change in velocity divided by the time it took for the velocity change to take place.

The acceleration of an object often changes through it's motion for a particular time interval. So, it is often useful to calculate the average acceleration.

The average acceleration is a vector and it is denoted by 'a'. the SI unit of average acceleration is metre per second squared (m/s2).

## Average Acceleration Formula

The formula of average acceleration can be written as change in velocity divided by the total time taken while the velocity is changing.

Average Acceleration = change in Velocity / time taken

a = Vf - Vi / tf - ti
a = ∆v / ∆t

Where,
• Vf is the final velocity
• Vi is the initial velocity
• tf is the final time
• ti is the initial time
• ∆v is the change in velocity
• ∆t is the total time taken while the velocity is changing.

In case, if there different velocities are given in the different time intervals, such as V1, V2, V3… Vn are the velocities for the time intervals of t1, t2 t3...Tn respectively.

In this kind of problems the average acceleration can be calculated by using this formula given below,

Average acceleration = v1+v2+v3…+Vn / t1+t2+t3...tn

### Average Acceleration Example

If a car starts from rest and reaches a velocity of 15 m/s in 5 seconds hence, the average acceleration of the car would be 3 m/s2. It means the velocity of the car will be increased by 3 metre per second every second.