MAKE YOUR OWN BAROMETER
Here is a classic weather experiment. With a few household items, you can make your own barometer. In case you don't know what a barometer does, it measures air pressure.
Materials:
1 small jar (baby food jar is perfect)
1 wide-mouth jar (1 quart)
2 balloons
2 rubber bands
1 flat toothpick
1 pair of scissors
1 bottle of glue
Procedure:
1) Cut the top off one of the balloons (the open end, or end with the hole)
2) Stretch the remainder of the balloon over the mouth of the small jar.
Use a rubber band
to hold it in place.
3) Glue the larger end of the toothpick to the rubber cover so it extends off
of the jar. Allow
some time for the glue to dry.
4) Carefully place the smaller jar inside the larger jar.
5) Cut the bottom off the remaining balloon.
6) Stretch the remainder of teh balloon over the top of the large jar. Use a
rubber band to hold
it in place.
7) Tie off the neck of the balloon so that the hole is closed.
8) Using the neck of the balloon, pull up and push down on the balloon to
change the air pressure
in the big jar.
9) Watch what happens to the toothpick.
What's Going On?
As you move the balloon over the big jar, the toothpick also moves up and down. When you push down on the balloon, the air pressure inside the jar increases and pushes the cover of the small jar down. This will cause the toothpick to point upward. When you pull up on the balloon, the opposite happens. The air pressure decreases in the big jar because the air has more room to spread out. This causes the lid on the small jar to expand and push the toothpick down.