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Yao: Rejected!

In this clip, we watch in open-mouthed wonder as 7-foot-6-inch leviathan Yao Ming becomes the property of 5-foot-9-inch Nate Robinson. Yao, whose defender had left him to guard the ball, receives a pass and leaves his feet for what should have been an easy one-foot jumper. But Robinson flies in from the weak side, takes a strong two-footed leap, and smacks the shot out of Yao’s hands (and back into his face) just as he shoots. Yao doubles over and brings his hands to his face, covering not only his injury but his deep sense of shame.

Before analyzing the physics of this maneuver, it’s tempting to assume the following things: Robinson, who gives up 21 inches to Yao, seems to be an immeasurably more talented athlete who plays with more energy and shows more heart. He certainly has a superior vertical leap (measure the height of Robinson’s shoes relative to Yao’s leg in this clip). But Robinson is not just 21 inches shorter than Yao. At 180 pounds, he’s 130 pounds lighter than Yao’s 310. Every time Robinson jumps, he’s moving less weight, and less weight takes less energy.

Just how much less energy? Let’s figure out how Yao’s and Robinson’s vertical leaps would compare if each expended the same amount of energy. The energy of a jump—and hence the work that must go into jumping—is proportional to both the jumper’s weight and how high he gets off the ground. Since we know that Yao weighs 58.1 percent more than Robinson does (180 divided by 310 equals 0.581), we can calculate that Yao’s vertical leap should be only 58.1 percent of Robinson’s.

Although updated numbers are hard to come by, Robinson’s vertical was measured to be 42 inches when he was drafted, and Yao’s as around two feet (a note to the viewer: two-foot vertical not on display in this video). Robinson can jump twice as high as Yao, so we can conclude that Yao would have to work twice as hard to reach the same height.

The lesson: Apply the same amount of energy to a smaller body and that body will jump higher every time. That, and Yao should dunk when he’s a foot away from the basket. —Michael Moyer

Related:

Flight of the Pole Dancer

Shake, Shake Chinook

Crane Overboard!

Goodbye, Moto

Stick That Landing

Sticking the Landing

Ordinarily, driving is pretty straightforward: You just point the wheels and go. But piloting an aircraft is trickier, because you not only must deal with complexities like the potential for traffic above and below the plane, but your roadway—the air—moves. Until it’s time to land, of course. Seamlessly transitioning from sky to asphalt is the most difficult thing a pilot regularly has to execute, especially when winds are strong and blowing from side to side (as in the crosswind landing featured in this video). But it’s easy enough to understand what a pilot should do in such circumstances, even if you’re too freaked out to ever in a million years attempt to do it yourself. All you need are vectors.

A vector describes how something moves; picture it as an arrow. The vector’s length describes how fast the thing is moving, and its direction tells you which way it’s going. If you threw a baseball straight up in the air, the vector that described its movement would start out long—the ball’s going fast—and pointed toward the sky. Then the vector would shorten as the ball slowed and, at the top of its arc, would flip downward and grow long again as the ball fell.

If an object is moving in or on a medium that’s also moving—a person on a moving sidewalk, a swimmer in water, a plane in the sky—you figure out how the two will move together by taking the vector for the object and the vector for the medium and joining them together head-to-tail.

In our example, the wind is whipping from left to right, so its vector points that way. For the plane to move straight ahead, its vector must cancel out the left-to-right vector of the wind. That means it has to point a little to the left, or into the wind.

Of course, once the plane hits the ground, it had better be pointing in the direction it’s moving. That’s why the pilot has to straighten the plane out at the last second. If he did it any earlier, the wind would start to pull the plane to the right; if he did it any later, the plane would hit the tarmac sideways and flip over onto its wing. And you thought parallel parking hard. —Michael Moyer

Related:

Flight of the Pole Dancer

Shake, Shake Chinook

Crane Overboard!

Goodbye, Moto

Page 1425 of 1657

June 2013: American Energy Independence

Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.

Online Content Director: Suzanne LaBarre | Email
Senior Editor: Paul Adams | Email
Associate Editor: Dan Nosowitz | Email
Assistant Editor: Colin Lecher | Email
Assistant Editor: Rose Pastore | Email

Contributing Writers:
Rebecca Boyle | Email
Kelsey D. Atherton | Email
Francie Diep | Email
Shaunacy Ferro | Email

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