|
Air Pressure Law of LaPlace
|
|
|
|
|
|
This Week's Experiment - #298 Balloon Pairs
This week's experiment is an old one that may trick you at first. Once you
think about it, it should make perfect sense. You will need:
2 identical balloons
a drinking straw
tape
a friend to help you
Inflate one of the balloons about half-full. Don't tie it off. Instead,
twist the neck of the balloon several times. Then carefully fit the end of
the balloon over one end of the drinking straw and use tape to secure it
tightly.
Blow up the other balloon, but only inflate it one fourth of the way. Twist
the neck of this balloon several times and attach it to the other end of the
straw as you did with the first balloon.
Now you should have a straw with a large balloon at one end and a smaller
balloon at the other. What would happen if you untwisted the necks of both
balloons? Think about it for a minute. Will the two balloons stay the way
that they are? Will air move from the large one to the small one? Will
air move from the small balloon to the large one?
OK, have you thought about it? Have you decided what you think will happen?
Good. Then let's try it. Carefully untwist the neck of one balloon.
Then untwist the other. What happens?
Most people are very surprised by the result. Some people think that the
pressure will equalize, resulting in two balloons the same size. Others
think that higher pressure in the large balloon will inflate the smaller
balloon. Instead, the small balloon collapses and all the air winds up in
the big balloon. Why?
When you allow the air to flow freely between the two balloons, the pressure
equalizes. If you have the same amount of pressure in both balloons, what
is the difference? Size. With round, elastic containers, such as balloons
and bubbles, size is very important. The larger the balloon gets, the less
pressure it takes to make it expand farther. This is known as the Law of
LaPlace. At the equalized pressure, the small balloon can resist, but the
larger balloon stretches. That lets air move from the small balloon to the
larger, making the size difference even greater and continuing the process.
This is part of the reason that it is so hard to inflate a balloon. When
you first start, you have a very small balloon, so you have to blow very hard
to stretch the rubber. As the balloon inflates, it gets easier and easier
as it gets larger and larger.
The same applies to bubbles. Use a straw to blow some bubbles in a glass of
milk. Looking from the side, you will notice that as the foam builds up,
the smaller bubbles are the roundest. Where a large bubble and a small one
meet; the large one will form itself around the smaller one. As with the
balloons, it is much harder to stretch the small bubbles out of shape.
It would be a shame to waste the glass of milk, so get some cookies to go
with it as you digest this week's science.
From Robert Krampf's Science Education Company
PO Box 60982
Jacksonville, FL 32236-0982
904-388-6381
krampf@aol.com
|
|
|
|
Nicholas Academy Index
|
|
Artists, wars, armour, castle games, recipes, geography, quizzes, fashions, pictures of weapons, music, old world maps, women of medieval times, medicine, language, and more.
|
Arabic, German, Japanese, Spanish, French, Italian, Latin, Russian. Games, free software downloads, free online lessons, newspapers, discussion groups, articles, history, culture, quizzes.
|
Play language arts games, improve your vocabulary, create customized puzzles, make your own book! Download free software in the form of shareware, freeware, and demos.
|
Math games, quizzes, fun websites, printable charts, coloring books, tools. Algebra, geometry, fractions, multiplication.
|
Play music games, take free music lessons, explore music theory and history, find great posters.
|
|
Explore animation, filmmaking, build online cities, create and share works of art, write stories, create your own web site, read creativity articles.
|
Science games and quizzes, fun science websites, posters, coloring books, kits, experiments, forensics labs and more.
|
Coloring books, countries of the world, games and quizzes, software downloads, posters, computer jigsaw puzzles, printables.
|
Science can be fun and understandable. Free Experiment of the Week, featuring experiments that are unusual, safe, dramatic, cheap, and fun. From Robert Kramp's Science Education Co.
|
Fun and affordable space items for kids, including toys, games, kits, food products, and more.
|
|
Educational science kits kids will love! Early science kit, DNA explorer kit, robot challenge, forensic lab, volcano kits, crystals.
|
All in one project labs, light kits, sound kits, motion and metal detectors, clap on/off kit, nerve tester and shocker.
|
Civil rights, African American writers, parts of speech, medieval, periodic table of elements, music, astronomy, world maps with flags, literature, poetry, dinosaurs, biology, cats, Japanese anime.
|
Coloring books for kids and adults. Civil war, plants, animals, states, middle ages, cultures, geometric designs, puzzles.
|
Online, via email or through the regular mail. College, accredited high school, free reading and phonics courses, foreign language, history, religion, and more.
|
|
Test your knowledge with these fast, fun, and educational quizzes. Roman numeral addition, world capitals, presidents in order, the elements, world flags, and more.
|
Roman numerals, addition, multiplication, order of statehood, state and world capitals, order of presidents, chemical elements, parts of speech, spanish numbers.
|
Reading systems, loan programs, flashcard, worksheet and test makers, game creators, board games, percentage calculator, puzzle creator, timeline template.
|
SAT, GED, ACT, practice tests, exam preparation. Standardized test practice, content standards listed by state, sample items, scope and sequence, aptitude, essential skills.
|
New and used low cost books and textbooks. Websites with open source books and loan programs.
|
|
Templates, ideas for personal, educational, children's, business sites, design tips and tools, registration and hosting information, step-by-step instructions, quick and easy web page, web building just for kids.
|
Books, posters, videos, software kits, curriculum, courses. Save on teaching supplies, receive free educational materials.
|
This site map lists nearly every page on our site, along with a short description.
|
|
|
|
Educational Poster Store
Hundreds of educational posters in different subject areas. Parts of speech, medieval, solar system, biology, world maps, Einstein, Martin Luther King. Science, math, literature, art, music, english, geography, social studies. If you don't know exactly what you're looking for, this is great to browse for ideas.
|
NASA Website Links
Educational resources include worksheets such as mazes, coloring pages, shuttle model instructions, crossword puzzles, space food tray instructions and grocery list, and more. See the Space Station Sky Watch, view a NASA Astronaut Application or the Space Shuttle Launch Schedule, learn about the U.S. Space Camp and Women in Spaceflight.
|
Zoobooks
Get a free Zoobooks issue and a tiger poster. Zoobooks are the all-in-one, everything-you-wanted-to-know but-didn’t-know-who-to-ask guide to the world’s most fascinating animals, birds, reptiles, and insects. For kids five to twelve.
|
|
