› › › PHYSICS EXPLANATIONS
The more the rubber bands stretch, the more force they
will have to push back on the gumball.
When the trampoline bounces the gumball into
the air, the gumball becomes a projectile. A
projectile
is a body upon which only the force of gravity is
acting. The path that projectiles take as they move
through the air can be predicted based on the speed,
angle, and height at which it was launched.
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The
pinball launcher is similar to the trampoline in
that it demonstrates the principles of springs and
projectiles. When a gumball lands in the pinball
launcher, you can manually pull back on the trigger
and release to launch the gumball back up and out of
the track and down to another section of track.
In the pinball launcher, there is a metal spring. When
you pull the trigger back, the spring compresses and
stores energy. When you release the trigger, the stored
energy is released and converts into kinetic energy,
which is transferred to the gumball, pushing it along
the track. The gumball is a projectile that glides along
the track, like a ball inside a pinball machine.
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The
pulley cups and wheel demonstrate a simple
machine called a pulley. To set it up, first attach the
wheel to the tower with a straight pivot post. Then tie
the two ends of the string to the two handles on the
cups. Follow the instructions on the next pages for the
specific lengths of string you want for each setup.
Then, guide the string over the pulley wheel and
position one of the cups so that a track will deposit a
gumball into it.
The pulley demonstrates how a downward force
(the weight of a gumball) applied to one side is
transformed into an upward force of the cup on the
other side. Pulleys can change the direction of a force,
and also the amount of force needed, to perform work.
If you place two gumballs in the second pulley cup,
you probably will need two or more gumballs to fall
in the first pulley cup before it exerts enough weight to
lift up the second.
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Finally, there is the
tip-over tube. Like the
pendulum, this demonstrates center of mass and
stable equilibrium. Attach the tip-over tube to the
tower with the angled pivot post and the tip-over tube
clamp. The tip-over tube should be positioned high up
in the clamp. More of the tube should be above the
clamp than below the clamp. When gumballs fall into
the tube, they will stay in the tube until the center of
mass extends outside of the stable equilibrium point
and the tube tips over, dumping the gumballs into the
track below.
Now that you know how all the various tracks and
stunts work, follow the step-by-step assembly
instructions on the following pages to set up three
different gumball machines and use the parts together.
Gumball Machine Maker
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