You're asking about the change in velocity over a period of time, which is known as acceleration.

Here's the breakdown:

* Velocity: Velocity is a vector quantity, meaning it has both magnitude (speed) and direction.

* Change in Velocity: This is the difference between the final velocity and the initial velocity.

* Time: The time interval over which the change in velocity occurs.

Calculating Acceleration:

Acceleration is calculated by dividing the change in velocity by the time interval:

Acceleration (a) = (Final Velocity (v_f) - Initial Velocity (v_i)) / Time (t)

Example:

Imagine a car accelerating from rest (0 m/s) to a speed of 20 m/s in 5 seconds.

* v_i = 0 m/s

* v_f = 20 m/s

* t = 5 s

Acceleration (a) = (20 m/s - 0 m/s) / 5 s = 4 m/s²

This means the car's velocity increases by 4 meters per second every second.

Important Notes:

* Units: Acceleration is measured in units of meters per second squared (m/s²).

* Direction: Acceleration can be positive (speeding up) or negative (slowing down). It can also be in any direction.

* Constant Acceleration: If the acceleration is constant, the velocity changes at a steady rate. However, acceleration can also vary with time.

Let me know if you have a specific scenario in mind or if you'd like to explore other related concepts!