I am confused with instantaneous vehicle speed and average vehicle speed. Instantaneous vehicle speed gives a speed at a particular instant of time. Now my doubt is what is this instant of time? In the sense if a speed sensor is connected to the vehicle to know the speed you have to read number of pulses say for 1 sec to determine the speed. So, if you say instant is it at the beginning or at the end of one second. And the pulses should be read for how much duration is it 1sec or 1 m sec?