Teens snap away! - photographs illustrating physics principles are taken by teens

Science World, Jan 12, 1996 by Chana Freiman

Here's a challenge: Look around your school or town for a physical-science principle at work (anything from moving matter to colorful chemistry). Sure, you can check your textbook or back issues of Science World for ideas. But as the photos on these pages show, you shouldn't have to look far. All were snapped by teens who entered their best shots in a High School Physics Photo Contest (see contest info, p. 16). Maybe their photos will inspire you to check out the physics in your world, point your camera, and click away!

Scary Hair

What's making this girl's hair stand on end? Static electricity (the buildup of electric charges) in her hair! The girl has her hands on a Van de Graaff generator, a machine that gives off electrons (negatively charged particles). The moving path of electrons, or current, flows through her hands, up her arms, and through the tips of her hair! Hair normally has a balance of positive and negative charges. But with extra negative charges picked up from the machine, each negatively charged hair repels the others for a hair-raising experience!

Floating Metal Ball

The camera and photographer Heather Ford actually appear in this picture. The shiny metal ball reflects their images as light rays strike the mirrored surface and bounce off. Their images appear distorted, though, because the convex (outward curved) surface of the mirror makes the reflected light rays spread out, instead of traveling in a straight line to your eye. That gives you a wide-angle view of the scene. (Where else have you seen mirrors like this?) There's also a physics mystery here, says Heather. If her left hand is holding the camera and her right hand is sticking out behind the ball, how is the ball "floating" in midair?

Rubbery Rose?

If you covered the left-side of this photo, could you identify the petals of this rose? Probably not. That's because the light rays reflecting off the rose slow down as they travel through dense substances like glass and water. The slowdown bends, or refracts, the light rays as they travel to your eye, giving the rose petals a warped look.

Beetle Mania

To soar into the air, this click beetle bends backward and inserts a spike on the back of its head into a socket on its back. That action stores up energy in the beetle's body, similar to the way a spring stores energy when you compress it. When the beetle's head pops out of the socket, the released energy makes the bug spring off the table. Adam Seeger captured the insect's in-flight positions on a single piece of film. in a darkened room, he kept the shutter (or "eye") of his camera open, and flashed a strobe light on the bug. Each time the light flashed on (about 15 times per second), it exposed the film and captured the beetle's position at that instant.

Bridge Basics

The triangular pattern created by the cross beams of this bridge gives the bridge its strength. When a train crosses the bridge, it puts tremendous stress on the beams. The triangular trusses (rows of triangles) transfer the weight of the train to the long support beams and ends of the bridge. Result: The train, cargo, and passengers cross safely. Why triangles? Try this activity: Form a rectangle with your index fingers and thumbs and have a friend push down on your fingers. What happens to the rectangle? Now use the same fingers to form a triangle and have your friend push down on the top point with the same force. Notice a difference?

Sticky Spoon

You could say this girl has a nose for physics. To make this nifty trick work, she wiped the dirt and oil off her nose and the spoon. Then she breathed lightly into the bowl of the spoon and stuck it to her nose. The water droplets in her breath help the spoon stick because there's a force of attraction between the water, the metal surface of the spoon, and the girl's nose. Scientists call this force of attraction between different substances adhesion. Of course, you still have to get the spoon to balance or gravity will pull it to the ground. Try it yourself at mealtime (but don't say we told you to!).