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Experiment 9: Springs
HERE’S HOW
1
Attach the
trampoline to the tower at any
location using the
straight pivot post.
Stretch the rubber bands around the
trampoline ring. The notches in the ring keep
the rubber bands from slipping off. Try to
evenly space the rubber bands around the
surface of the ring. Position the trampoline
at an angle such that when a gumball falls
on it, the gumball bounces into the next
track segment.
2
Drop a gumball onto the trampoline. Repeat
with the trampoline set at different angles.
Experiment 10: Projectiles
HERE’S HOW
1
Attach the
pinball launcher to the tower at
any location.
2
Place a gumball in the launcher. Pull back
on the trigger and release. What happens?
Rubber band
color may vary.
Straight
pivot post
Rubber
bands
Trampoline
ring
Pinball
launcher
WHAT’S HAPPENING
The
trampoline is a window into two more huge
realms of physics: springs and projectiles. The
rubber bands in the trampoline work like a
spring.
When a moving body stretches or compresses a
spring, it converts its kinetic energy into potential
energy stored in the spring. Then, the spring
bounces back and pushes back on the body. The
amount of force exerted on a spring is
proportional to the amount, or distance, that the
spring stretches or compresses. The more
momentum a gumball has when it hits the
trampoline, the more the rubber bands will stretch.
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.
WHAT’S HAPPENING
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.
The
pinball launcher is similar to the trampoline
in that it demonstrates the principles of springs
and projectiles. 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.
10
