Sunday, November 20, 2005
How to read a Tachymetre
Okay this is pretty interesting, at least to me -- I've had a Tachymetre scale on my stopwatches for a while now and the only thing I ever did with the scale was to calculate speed of cars. I just learned that the scale is actually a logarithmic scale which can calculate all kinds of things based on a "per hour" scale.
1) To calculate the speed of a car over a known distance (say 1kilometre or even 1mile) press the top chronograph button when entering the fixed distance press it again when at the end of the fixed distance. If the time elapsed is 45 seconds the second hand points to the figure 80 on the Tachy scale. If the fixed distance is a Kilometre then the car is traveling 80 kilometres per hour. If the distance covered is a mile, then the speed is indicated in Miles per hour, in this example 80 MPH...
2) To calculate the output of a machine, start the chronograph and count a set number of units made, at the end of this number stop the chronograph. Say, a printing press produces 100 newspapers in 30 seconds -- when you stop the chronograph on the watch at 30secs, reading off the tachymetre scale, it says 120, which means that 100 x 120 = 12000 newspapers per hour.
Interesting huh? No? Oh well...