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Last updated April 16, 1996 |
I n conjunction with the exhibition What About AIDS?, which runs through June 2, 1996, the Exploratorium presented a special lecture/discussion on emerging viruses on March 27th. In these RealAudio sound files, journalist Lisa Krieger talks about emerging viruses from public-health, policy, and journalistic stand points,
and Dr. Donald Francis talks about his experiences with emerging infections, while working in public health over the last few decades.
Click HERE to download the RealAudio player. Related Sites What About AIDS? Science, Art & Human Stories Centers for Disease Control and Prevention (CDC) 
S o what's the catch? Nothing. NASA's Jet Propulsion Laboratory is offering a free CD for students and teachers. The CD is great for students ranging from middle school to college level. It contains radar images of sites around the world as seen before and during the SIR-C mission, which flew aboard the space shuttle in 1994. The CD contains a Web site and uses Netscape as the interface. The CD is available only in Macintosh form. Preview the CD at:
http://southport.jpl.nasa.gov/
It can be ordered free at:
http://southport.jpl.nasa.gov/
or by mail (also free) from:
"What's New in in the World of Science" is published the middle of every month. Remember to check back next month and see "What's New"! |
Comet Hyakutake, which surprised most astronomers with its brightness and its close pass, was discovered on January 30 by amateur astronomer Yuji Hyakutake. Coming right on the tail (figuratively speaking) of Comet Hyakutake is Comet Hale-Bopp, which may be visible to the naked eye early next year.
Comet Hyakutake: Adapted from Sky & Telescope, April 1996
Fold a 3 x 5 inch index card 3/4 inch from each edge at a right angle. Place the card on a table so that the cards stand on the folded ends. What will happen when you blow (hard) through the tunnel under the card? I bet you think that the card will go sailing. Well, try it!
Surprise! The card goes nowhere. As a matter of fact, if you watch carefully, you'll notice the card "hunker down" while you blow. The harder you blow, the greater the force pushing down on the card.
Ron Hipschman
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| The Learning Studio | The Exploratorium |
This is due to an effect discovered by mathema-
tician Daniel Bernoulli. Bernoulli noticed that the pressure in a moving fluid (air is a type of fluid) is less than when the fluid is stationary. When you blow beneath the card, you reduce the pressure under the card, but the atmosphere is pressing just as hard on the top as it was without your attempts The harder you blow, the more pressure pushes down. Try blowing air over the card. Now it takes off! Here, the pressure is reduced above the card so that the air under the card pushes it up. In hurricanes, the fast-moving air over the roof of a house reduces the pressure in much the same way. The air inside the house then blows the roof off!
