It is always an average speed that we measure.
Even quite a sophisticated instrument designed to show 'instantaneous speed' works out an average speed, but to be classed as being able to read instantaneous speed it needs to be able to work out how far the object travels in a very short time period indeed - measured in microseconds.
In science lessons we usually work out an average speed for a given time period such as a minute, because the error in measuring smaller time periods would be too great. |