Water Rocket at Liftoff
Actually it was pitch dark in the garage when these water rocket pictures
were taken. For this photograph I'm just pretending to watch the rocket by
looking at where I think the rocket will be when the picture is taken.
It's also difficult to position the rocket so it passes through the infra-red
light beam above it. Since we can't see the infra-red beam we first had to
determine where it was by moving our hand or an object around the general
area and watch the volt meter connected to the receiver at the other end of
the beam. We watched until the volt meter made a significant swing,
indicating to us that we had found the beam by blocking its path to the
sensor. I had to position the rocket so it was nicely framed in the camera
and also directly underneath the invisible beam. After the lights were shut
off I had to be careful not to tilt the rocket to one side when I launched it,
which it had a tendency of doing.