I've just come back to physics a decade after school and starting again from the bottom so this might be a very basic, even silly question. Reading about speed, velocity etc the text talked about instantaneous speed being being different to average speed in that it is the speed of an object at any given instance in time. But wouldn't this idea lead to an equation for speed being s=0/0 since at any given instant distance and time would be 0. Distance cannot be >0 if time is 0 and time cannot be >0 because then any value for s would still be an average. Have I gone wrong somewhere or is instantaneous speed really just average speed where the change in time is infinitesimally small?