Instantaneous Velocity and Speed
To find the velocity at a specific time, called the instantaneous velocity,
we take the limit of the average velocity as the time interval becomes very
small. Mathematically, this process defines the derivative of the
position with respect to time,
The instantaneous velocity can be found as the slope of the tangent to
the curve on an x versus t graph at that particular time.
The average velocity from t=5 s to 7s is marked in the
graph. Use the slider 1 (Dt) below the graph to reduce the time
interval (Dt) to near zero and watch
how the velocity changes.
slider 1
slider 2

Compare this with the exact value of the
instantaneous velocity found by taking the derivative. You can also use
the slider 2 to get the instantaneous velocity at some other point.
Script by Dr. Mohamed S.
Kariapper using Physlets from



The speed is the magnitude of the velocity.