Acceleration Formula with Velocity and Time

In this article, we will look at the acceleration formula with velocity and time. Before going any further let us define what is acceleration.
Acceleration is change in velocity over time
There are two ways to find the acceleration 

In this article, we will look at the formula for acceleration with velocity and time. We use the acceleration formula with velocity and time when we do not have any knowledge of force acting on the body. We only have information about

  • Change in velocity
  • Time

Acceleration formula with velocity and time

As mentioned earlier acceleration is the change in velocity over time. So acceleration is the change in velocity divided by time. Mathematically,

acceleration formula


  • \(v_1\) is the initial velocity
  • \(v_2\) is the final velocity and
  • \(t\) is the time taken to reach ending or final velocity from starting or initial velocity then
formula for acceleration


  • acceleration \(a\) is in \(m/s^2\)
  • velocities \(v_f\) and \(v_i\) are in \(m/s\)
  • \(\Delta v\) is short form for change in velocity.
  • and time \(t\) is in \(seconds\) 

Acceleration formula important facts

  1. Acceleration s a vector quantity. Acceleration has both magnitude (a value) and direction
  2. The direction of acceleration can be different from the direction of velocity.
  3. Unit of acceleration is \(m/s^2\)
  4. Acceleration can be negative and positive. It is negative when velocity decreases with time. It is positive when velocity increases with time.
See also  Examples of Static Friction

Solved Questions on acceleration formula with velocity and time

Question 1. A bus decreases its speed from \(80\,\,m\,s^{-1}\) to \(60\,\,m\,s^{-1}\) in 5 seconds. Find the acceleration of the bus.
Solution. Here it is given that initial velocity,
final velocity,\(v_f=60ms^{-1}\)
Time \(t=5\,s\)
We have to calculate the acceleration from this data. Now from the acceleration formula we have
putting in the respective values 
Note that the answer is negative. This negative sign indicates that velocity is decreasing with time.

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