Running count
I read somewhere that the Greek mathematicians always carried a bag of stones with them in case they had to calculate something. That may be why the etymology of ‘calculus’ is ‘stone (used in reckoning)’.
Be that as it may, counting is not easy. Especially when you are disrupted. Flight attendants sometimes use a little device they click for every passenger to get a correct head count.
The latest fad is a step counter to stimulate your exercise walks. Today’s challenge is to explain how a step counter works.
A related puzzle. When a soccer player is substituted during a game, sometimes how many km he has run is displayed on the TV screen. How on earth is that calculated?
November 29th, 2007 at 9:28 am
A step counter, or pedometer, works based on the force of the impact experienced with every stride. It is designed such that the vertical force, or shock, is translated into movement inside the device (such as a magnet moving past a sensor) which registers a “count” for each step. If you walk very carefully, heel-to-toe, minimizing the impact to your body, the pedometer will not register. Or, if you take a drive down a very bumpy road, it may register some steps not taken. I don’t use one, but my son enjoyed the counter we placed on his bicycle which tranlates each wheel rotation into distance traveled and his current speed. He enjoys biking more when he can work towards a distance goal.
As for the soccer player, I would assume this is an approximation. Several methods could be used depending on the desired accuracy of the approximation. You could count strides and multiply by an average stride length. You could count minutes played and multiply by an average speed with which the player is always moving – faster for a forward than a goalie. Or perhaps they’ve implanted tracking devices which communicate with global positioning sattellites under their skin?