By: Beth Post

Explorit is pleased to announce the fall line-up of lectures for the 1998-99 Cutting Edge of Science lectures series. The series of free public talks, sponsored by Novo Nordisk Biotech with support from the Davis Senior Center, will kick off on Tuesday, September 15 with "Electric Cars: Can They Go the Distance?" presented by UC Davis professor Andrew Frank.

Dr. Frank is a member of the Mechanical and Aeronautical Engineering faculty at UC Davis. He has worked for 25 years on the design of hybrid electric vehicles - cars that use both electric and gasoline fuel sources. Dr. Frank's presentation will explore how the next generation of hybrids can meet the challenges of improving air quality and reducing fuel consumption while meeting customer demands for range and speed.

Dr. Kelly Stewart of UC Davis' Anthropology Department will be the second cutting edge scientist in the series, with her lecture, titled "Gorilla Conservation in the 21st Century," on Tuesday, October 20. And on Tuesday, November 17, Kat Anderson will present "Tending the Wilds: How Native Americans Used and Shaped California's Landscapes."

All lectures in the series are free to the public, are held at the Davis Senior Center, 626 A Street, and begin at 7:30 p.m. For more information, call Explorit at (530) 756-0191.

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Plans are still in the making for Explorit's Grand Opening of its new West Wing Expansion, to be held on Sunday, September 20 from 1:00 to 4:30 p.m. Demonstrations, hands-on activities, games, stories and songs are all part of the excitement and celebration in store for visitors. All the events are free to the public.

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Speaking of excitement, you can experience some heart-stopping thrills on many of the rides at the California State Fair. If you're looking for free excitement, however, you're only likely to get it at the midway when you experience "free" fall on some of the big rides. Free fall is the phenomenon that occurs when a falling object is moving under the influence of gravity only. There are rides completely devoted to the experience of free fall, where riders are carried in a car up to some eye-popping height, suspended temporarily (truly a "suspenseful" moment!), then plunged straight to earth. Of course, the riders don't smash to the ground; an escape track gradually curves to earth at the end of the ride, and a length of straight track allows the car to brake - and riders to catch their breath.

One of the most exhilarating aspects of free fall rides is the momentary experience of weightlessness. How does such an apparent loss of gravity come about? It has to do with the very nature of free fall itself.

As riders are being hauled up in a free fall car, the force produced by the lifting machinery is opposed by gravity, which is pushing them earthward (as always). This is experienced as being "pushed" into the seat of the car. Once dropped, however, the riders are moving at the same rate as the car itself, both "pushed" earthward with equal gravitational force and no opposing force (ignoring air resistance again). The sensation is one of the seat dropping out from beneath the rider, creating a sense of weightlessness.

You can demonstrate free fall at home (though not on yourself). Punch two holes, about 1/4-inch in diameter, into opposites sides of a paper cup. Fill the cup to the rim with water. What happens? As long as you're on earth, the force of gravity should cause the water to flow out of the cup through the holes.

Refill the cup, but this time cover the holes with your fingers while you do so. Now drop the cup from an elevated height. What happens to the water inside the cup as it falls? If you're still on earth, the water shouldn't flow out of the holes, because it is falling at the same rate as the cup.

To learn more about the science behind amusement park rides, try the cool web site at www.learner.org/exhibits/parkphysics/index.html. Or "fall" into Explorit's current exhibition, The Way the Ball Bounces: The Science of Toys and Games. There you can perform more free fall tests as you explore the physics of falling and flying. Here's hoping you enjoy the fall!

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Explorit Science Center is located at 3141 5th Street in East Davis. The current exhibition is The Way the Ball Bounces: The Science of Toys and Games. Public hours are Saturday from 11:00 a.m. to 4:30 p.m., Sunday from 1:00 to 4:30 p.m., and Tuesday through Friday from 2:00 to 4:30 p.m. Regular admission is $3; members, teachers (with school ID) and children under 4 are free.