Spin master: a teen masters the ups and downs of yo-yos, putting a cool new spin on an old toy.

Fourteen-year-old Sterling Quinn can send his yo-yo zinging off its string, catch the flying orb behind his back, and weave the yo-yo's string into webs so complicated you lose count of all the toy's flips and turns. Yo-yos have been around for thousands of years, but only recently have yo-yoers like Sterling been able to pull off such jaw-dropping tricks.

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With the help of high-tech yo-yos designed to work with the laws of physics, Sterling--Washington State s yo-yo champion--and a new generation of yo-yoers are turning an ancient game into an extreme sport.

LEARNING THE ROPES

Sterling started toying around with yo-yos in 2004, but it wasn't until he watched the first annual Pacific Northwest Yo-Yo Championship in Seattle that he became officially hooked.

Sterling was mesmerized by the tricks performed by the competitors. "I saw how amazing they were and wanted to be that good," he says.

Inspired, Sterling joined a local yo-yoing club named Strung Out, where the older members guided him through tricks. A few years later, Sterling was beating these long-time yo-yoers at their own game.

Sterling now knows more than a hundred tricks. But before he ever attempted stunts with names like Split the Atom, Double or Nothings, and Lacerations, he had to learn a fundamental part of all yo-yo moves--getting his yo-yo to "sleep."

SOUND ASLEEP

Sterling sends his yo-yo to sleep--so it remains spinning at the bottom of its string--by quickly throwing down his yo-yo. As the toy falls, the string that's looped around its axle begins to unwind, causing the yo-yo to rotate. Because the yo-yo is moving in a downward line, it builds up linear momentum (an object's mass times its velocity); but it also gains angular momentum, or momentum from rotating. It's this angular momentum that causes the yo-yo to sleep.

To get the yo-yo to wind back tip, Sterling jerks his hand upward. This action briefly adds slack to the string, allowing it to rub against the spinning yo-yo. Friction, a force of resistance, between the string and the axle causes the two parts to grip. This leads the spinning yo-yo to rewind up the string.

Pulling off a difficult yo-yo trick requires Sterling to keep his yo-yo sleeping throughout the entire maneuver, even while it's whirling through the air or cradled in a net of string. If the yo-yo stops spinning, it won't have enough energy to zip back up to his hand so that he can launch his next move.

TRICKED OUT

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Competition yo-yos like Sterling's have been redesigned to maximize their ability to snooze (see Nuts & Bolts, p. 17). Getting a yo-yo to sleep longer gives yo-yoers time to complete wilder tricks than ever before.

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Toy engineers' first improvement was to make yo-yos heavier by attaching metal edges. Newton's first law of motion states that all objects have inertia, or resistance to change in motion. As an object's mass increases, so does its inertia. The increased weight makes it hard to stop the yo-yo once it starts spinning, explains Sterling.

New yo-yos also have ball bearings--a metal wheel containing steel spheres--fitted around their axles. When a yo-yo spins, the outside of the bearing rolls smoothly over the balls. "The ball bearing reduces friction," says Sterling. That means the slick bearing won't grab onto the string as easily, so the yo-yo can continue sleeping for minutes at a time.

YO-PROS

Yo-yos now sleep so soundly that a tug is not enough to get the spinning orb to return to a player's hand. To wake up their toys, professional yo-yoers attach a ring of rubbery or textured material to the inside walls of their yo-yos, says Sterling. The material helps snag the yo-yo's string when a player gives a yank, so the toy returns to the palm of their hand.

The yo-yoers Sterling competes against are usually between 12 and 25 years old. At yo-yo tournaments, each person gets three minutes to show off a routine of tricks that he or she hopes will win the most technical and performance points from the judges. Sterling likes to time his tricks to alternative rock music to get the best effect.

Why are kids like Sterling getting into yo-yoing? "You can do it anywhere, and it's fun by yourself or with a group of people," says Sterling. And unlike another of his hobbies, skateboarding, you're less likely to get hurt. Unless you count string burn on your fingers, he jokes.

nuts & bolts

Today's yo-yos have gone high-tech. New technical upgrades allow players to perform a wide range of complex tricks.

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Try these tricks: Duncan has created this easy guide so you can try your hand at three beginner yo-yo tricks. You don't need a high-tech yo-yo to give these stunts a whirl

(1) THE SPINNER

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BEGIN BY HOLDING THE YO-YO IN YOUR HAND-PALM UP. NOW, THROW THE YO-YO OFF THE END OF YOUR HAND WITH A FLICK OF THE WRIST.

THIS IS THE TRICK YOU SHOULD LEARN TO DO WELL AS IT'S THE STARTING POINT OF MANY OTHER TERRIFIC TRICKS.

HINT!

NEVER TOUCH THE YO-YO WITH YOUR THUMB!

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AS SOON AS THE YO-YO IS RELEASED FROM YOUR HAND. DON'T MOVE AND THE YO-YO WILL HANG SPINNING AT THE END OF THE STRING.

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GIVE THE STRING AN EASY JERK BEFORE THE YO-YO STOPS SPINNING IT'LL CLIMB THE STRING TO RETURN TO YOUR HAND!

(2) WALKING THE DOG

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HERE'S A REAL CUTIE THAT'S PRETTY EASY TO DO. FIRST, THROW A FAST SPINNER ...

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THEN LOWER YOUR YO-YO TO THE FLOOR REAL EASY-LIKE ...

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AND LET IT WALK IN FRONT OF YOU FOR A SHORT DISTANCE!

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DO NOT ALLOW ANY SLACK IN THE STRING UNTIL YOU'RE READY TO BRING THE YO-YO BACK. A SLIGHT JERK ON THE STRING WILL RETURN THE YO-YO TO YOUR HAND.

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(3) ROCKING THE BABY

PRACTICE THIS WITHOUT SPINNING THE YO-YO. LET IT HANG THE FULL LENGTH OF THE STRONG.

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WATCH YOUR LEFT HAND REACH OVER AND TAKE HOLD OF THE STRING. LIKE THIS ...

[ILLUSTRATION OMITTED] NOW DROP YOUR RIGHT HAND DOWN TO CATCH THE STRING ABOUT FOUR INCHES FROM THE YO-YO. AND YOU HAVE FORMED A TRIANGLE.

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DROP YOUR LEFT HAND DOWN AND SWING THE YO-YO UP AND BACK THROUGH THE TRIANGLE!

NOW TRY IT WHILE DOING A FAST SPINNER, TO MAKE IT RETURN, FLICK THE YO-YO WITH YOUR RIGHT HAND AND THEN CATCH IT WHEN IT POPS BACK TO YOU!

Spin Master

* What is the most important trick that a competitive yo-yoer must learn?

* Yo-yos, along with juggling bails, are considered skill toys. You need patience and practice to pull off tricks with these toys. What types of "skills" would a person need to become a good yo-yoer?

DID YOU KNOW?

* The yo-yo was first introduced to America in the 1920s by Pedro Flores, who brought the toy from his native Philippines.

* The term yo-yo means "come back" in the Philippine language of Tagalog. Early versions of the toy were also called "Twirler" and "Whirl-a-gig."

* In 2005, 30-year-old Tim Redmond got his yo-yo to sleep for 16 minutes and 17 seconds--the longest yo-yo spin to date.

CRITICAL THINKING:

* Today's yo-yos have strings looped loosely around the bar connecting their two halves. But the first yo-yos had strings tied directly to their axels. Why would a tied string limit the number of possible yo-yo tricks?

CROSS-CURRICULAR CONNECTIONS:

HISTORY: Research the origin of the yo-yo and how the toy has changed over time. Then create a timeline highlighting design improvements made to the yo-yo. Be sure to explain how each improvement affected the art of yo-yoing.

RESOURCES

* For more on yo-yo physics, read the Science News article "Reinventing the Yo-Yo," by Peter Weiss, at: www.sciencenews.org/articles/20040417/bob9.asp

* This Web site provides students interested in yo-yoing with how-to videos: www.howtoyoyo.com/

DIRECTIONS: Answer the following in complete sentences.

1. What physical forces help put a yo-yo to sleep?

2.You can get a sleeping yo-yo to wind back up by jerking your hand upward. Explain the physics that allows this to happen.

3. To maximize a yo-yo's snooze time, toy engineers made competition yo-yos heavier by attaching metal edges. Explain how Newton's first law of motion allows heavier yo-yos to sleep longer.

Answer key

1. When you throw a yo-yo down quickly, the toy falls. As the string that's looped around the yo-yo's axle begins to unwind, it causes the toy to rotate. Because the yo-yo is moving in a downward line, it builds up linear momentum; but it also gains angular momentum. It's this angular momentum that causes the yo-yo to sleep.

2. By jerking your hand upward, you briefly add slack to the string, allowing it to rub against the spinning yo-yo. Friction between the string and the axle causes the two parts to grip. This leads the spinning yo-yo to rewind up the string.

3. Newton's first law of motion states that all objects have inertia, or resistance to change in motion As an object's mass increases, so does its inertia An increased yo-yo mass makes it harder to stop the toy once it starts spinning.