### Hammerhead flight path with velocities

The line with marked points shows the flight path of the hammer head
during a downstroke. The arrows show selected velocity vectors.

The selction is based on the necessity to choose points for
calculting delta-x and delta-y such that the +\-0.6 cm error of
measurement doesn't propagate through the velocity calculation and
overwhelm the value for V.
Even though we have data points at 1 millisecond intervals, for
calculating velocity and acceleration we have to choose points about
11 ms. apart.

Updated 9 May 2000 -- Mike Spencer