A
roller coaster loop-the-loop is a sort of centrifuge, just like a merry-go-round. As you approach
the loop, your inertial velocity is straight ahead of you. But
the track keeps the coaster car, and
therefore your body, from traveling along this straight path. The
force of your acceleration pushes
you from the coaster-car floor, and your inertia pushes you into the
car floor. Your own outward
inertia creates a sort of false gravity that stays fixed at the bottom
of the car even when you're
upside down. You need a safety harness for safety, but in most
loop-the-loops, you would stay in
the car whether you had a harness or not.
As you move around the loop, the net force acting on your body is
constantly changing. At the very
bottom of the loop, the acceleration force is pushing you down in the
same direction as gravity.
Since both forces push you in the same direction, you feel especially heavy
at this point. As you
move straight up the loop, gravity is pulling you into your seat while the
acceleration force is pushing
you into the floor. |
At the top of the
loop, when you're completely upside down, gravity is pulling you out of your seat,
toward the ground, but the stronger acceleration force is pushing
you into your seat, toward the sky.
Since the two forces pushing you in opposite directions are nearly
equal, your body feels very light.
As in the sharp descent, you are almost weightless for the brief moment
when you are at the top of
the loop. As you come out of the loop and level out, you become heavy
again. In a loop-the-loop,
the intensity of the acceleration force is determined by two factors:
the speed of the train and the
angle of the turn. As the train enters the loop, it has maximum kinetic
energy -- that is, it is moving
at top speed. At the top of the loop, gravity has slowed the train down
somewhat, so it has more
potential energy and less kinetic energy -- it is moving at reduced
speed.
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