in the previous video I set up a pendulum that sort of traced out a
lissajos pattern and I thought would it be cool to graph this so I set this
swing that allows me to trace the motion just by putting a pen on top of this
notepad
so unfortunately the motion died out rather quickly because I have too much
friction from the pen even though it's a fountain pen with very light pressure on
the paper this pattern goes from a straight line to eventually one like
this is because the period of swing in this direction is different from the
period of swing in this direction is because for swinging this way the length
of the pendulum is from here to this corner for much of the weight whereas
swing this way it all swings in parallel so the length
of swing is from here to here middle of the board and that's a slightly shorter
length now I'd like that swing to last a little bit longer so I'm just going to
add some links to this swing which will give it more inertia
I think I'd like these lines a little bit further apart so I think what I need
is I need this swing to be more different from this swing and I think if
I put the weights further apart that will accentuate the difference of
distance from one axis to another which should throw the periods out a bit
further
so with two different periods of swing first I started out in phase tracing a
line like this then they went circular and then completely out of phase like
this and then they went back in phase before it completely died out so I
thought it'd be interesting if the ratio of swings on here wasn't close to 1 to 1
maybe something like 3 halves and for that I have to shorten the length of
this pendulum in one direction and I figured by keeping these from going side
to side at about this level here that might work out now the swing is roughly
proportional to the square root of the length 29 centimeters from the swing
here to get that period
rather than wasting a lot of paper I'm timing the swing to make sure I got the
relative periods about right and then making minor adjustments I didn't get
the parents quite right but I also think I want a little bit more weight on there
just so it swings a bit longer
I moved these bars up a bit to make this pendulum longer which set the ratio to
about 3 to 4
and finally trying out a two-to-one ratio
well that was kind of fun to experiment and here's various shapes that I've
drawn with it kind of like a rose engine except it's much simpler of course the
same thing could be achieved just by applying the king sinusoids against each
other on the computer but something physical is always way more fun