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Exciting Example of Everyday Phenomena
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Demo #27 On The Space Shuttle You Can Eat All You
The
Earth is so big; it has a lot of gravity that keeps us all planted on its
surface. Since the Sun is gigantic compared to the Earth, it has even more
gravity. The Sun's gravity is what keeps our Moon and all the planets in orbit,
even far-off Pluto, some 6 billion kilometers (3.5 billion miles) away. Gravity
is powerful. But when astronauts go up in the Space Shuttle, they orbit just 400
kilometers (250 miles) above the Earth, much closer than the Moon. They're
pretty close, yet they start to float around. It's as though there's no gravity
at all. How can this be? Shuttle astronauts float weightlessly because they're
falling. Flick a penny off a table, and it will still fall. But it lands some
distance from the table edge. Objects in orbit, like astronauts and shuttles,
are going so fast that they fall around the Earth. Things that are falling can't
be weighed. If you went skydiving and you took a scale with you as you jumped
out of the plane, the scale would read "0." Both you and the scale
would be falling, so you couldn't press against it. It’s the same with
astronauts and their equipment.
See
how it works with a Weightless Clothespin of Science!
What
You Need:
 |
Two
clothespins |
|
One
big, thick rubber band. |
What
You Do:
|
Clip
your clothespins onto opposite sides of the rubber band. |
|
Hold
up one of the clothespins. The weight of the other clothespin pulls down
on the rubber band, making it into an oval or stretched shape. |
|
Let
go of the clothespin. |
What's
Happening?
Gravity pulls the clothespins and rubber band toward the floor. But since they are falling together, the bottom clothespin will no longer seem heavy to the rubber band. To help keep a close eye on your experiment, get a friend to drop it from a high place or throw it into the air outside. If you watch carefully, you'll see that the rubber band stops being stretched by the weight of the clothespins. It goes back to its shape. The bottom clothespin does not pull down when it’s falling. The whole rubber band/clothespin system is falling. It's weightless! Astronauts in the Space Shuttle float around for the same reason -- since they're falling, they have no weight!