Calculate initial velocity from final velocity, acceleration, and time or from displacement, acceleration, and time in m/s, km/h, mph, or ft/s.

One-dimensional motion with constant acceleration. Choose one positive direction; velocity, displacement and acceleration use that same sign convention.

Optional settings

Select the sign for your chosen axis. A preset fills acceleration; local gravity varies.

Initial Velocity Formula

The following equation calculates initial velocity for one-dimensional motion with constant acceleration.

V1 = V2 - t × a
  • Where V1 is the initial velocity
  • V2 is the final velocity
  • t is the time
  • a is the acceleration

To calculate the initial velocity, subtract the product of the time and acceleration from the final velocity.

Initial Velocity Definition

Initial velocity is the signed velocity at the start of the chosen time interval.

Initial Velocity Example

The following example reviews how to use the above equation to determine initial velocity.

  1. First, measure the final velocity of the object.
  2. Next, determine the total time that has passed.
  3. Next, determine the acceleration acting on the object during that time period.
  4. Finally, plug those three values into the formula above to get initial velocity.

For example, given V2=5, a = 2, t =2, solving: V1 = 5 − 2 × 2 = 5 − 4 = 1 m/s, with V2 = 5 m/s, a = 2 m/s² and t = 2 s.

FAQ

What is initial velocity?

Initial velocity is a movement an object has at the start of an observation period in which an acceleration starts to act on the object.

Initial Velocity Calculator screenshot
initial velocity formula