This is a
plot of vertical velocity against time with
velocity in an upwards direction as positive
(velocity is a vector quantity - if you go
the other way, it becomes negative, unlike
speed which cannot become negative). Like the
Height against Time quick graph, it was
produced using a 4 x 6 font, running the
water rocket simulator in a DOS box.
Again, as the mouse moves over the plot
area, the values for its position on each
axis are printed on the graph next to each
axis using the appropriate units.
Like the height graph, the different
stages of the rocket's flight are in
different colours. With a launch rod, the yellow
portion of the flight gives the rocket a good
start, producing around a quarter of the
final velocity in a very short time and using
very little water in the process. After that,
the blue
portion - representing the water thrust part,
long here because of using a t-nozzle -
pushes the velocity up to its maximum. The cyan
part of the flight, representing the air part
of the thrust, shows a reduction in velocity
and the red
portion, representing the coasting phase
takes the flight through to the apogee, where
the vertical component of velocity is equal
to zero. Once the rocket has reached its
apogee, the velocity becomes negative and the
parachute starts its deployment (magenta)
with a steady negative (downward) velocity
for the duration of the flight with the
parachute open (green)
until it hits the ground.
The other quick graphs (including the
statistics) can be accessed by pressing the
initial letter for each page.