› › › EXPERIMENTS
WHAT’S HAPPENING
When a gumball enters the cup at the top of the
pendulum at the right angle and the right speed,
it causes the pendulum to turn on its axis and the
gumball is dropped down to a lower track. When
a gumball is dropped straight down into the
pendulum cup, it often is not enough to make the
pendulum tip over on its own.
A
pendulum is a weight suspended from a
pivot that can swing freely. It demonstrates
center of mass and stable equilibrium.
Center of
mass is a point on a body representing the mean
(or middle) position of the mass of the body —
mass on all sides of this point balances out.
When the pendulum is stationary, it is said to be
in stable equilibrium.
Equilibrium is the state of
a body at rest or in unaccelerated motion in which
the result of all forces acting on it is zero. A body is
in
stable equilibrium if its center of mass is located
vertically above its base of support. If its center of
mass lies vertically above its tipping line (the edge
of the base), then it will wobble or fall over. The
slightest movement will make it tip over. But its
stability also depends on the force needed to push it
off balance.
The pendulum has been specifically designed
with a counterweight at the bottom that offers just
enough inertia to keep the pendulum stable until
the gumball enters the cup and knocks it out of
stable equilibrium.
Track
without
dominos
Experiment 7: No obstacles
HERE’S HOW
1
You can also use the
domino track without
the dominos and post as a simple 90-degree
smooth track. Test it out!
Experiment 8: Pendulum
HERE’S HOW
1
Attach the
pendulum to the tower
at any location using the
angled
pivot post.
2
Drop a gumball into the pendulum
cup. What happens?
3
Add a segment of track to the
tower in a location such that it
will deposit a gumball into the
pendulum cup. Roll a gumball
down the track into the pendulum
cup. What happens now?
Tips for the pendulum:
The pendulum might need a little push to get it
moving if the gumball doesn’t fall into it at the
right angle or the right speed.
The pendulum might not always dump the
gumball into the same spot below. This depends
on the rotational speed of the pendulum!
Pendulum
Angled
pivot post
Gumball Machine Maker
9
