Instantaneous and average velocities

This applet allows you to visualise the limiting process by which we identify an instantaneous velocity as the average velocity over a vanishingly small interval (Key Point 1.5). In this case we have a particle moving at constant speed in a circle. You can increase or decrease the length of the interval over which the average velocity is measured by clicking on one or other of the two duration buttons.

Investigate what happens when you make the interval very small.

Then (to make a rather different point) watch what happens when you make the interval comprise a whole circuit.