TURN, TURN, TURN: The way a dancer holds his or her body can affect the speed of rotation. Once in the air, a dancer controls his or her rotation speed by closing or opening the body position. A closed position, with the arms and legs pulled in tight against the body, decreases resistance and increases rotation speeds. On the other hand, an open position, in which the arms and legs are allowed to swing away from the body, causes the speed of rotation to decrease. That's why dancers tighten their body positions when performing twists or jump turns.
HANG TIME: Michael Jordan earned the nickname 'Air Jordan' because of his seemingly longer 'hang time' making jump shots in games, but this is an illusion. How high someone can jump depends on the force used to push on the floor when starting to jump, which in turn depends on the strength and power of the jumper's leg muscles. The harder and more powerful the jump, the higher and longer the flight. In order to leap four feet into the air, the hang time would be 1.0 seconds. Jordan had a few tricks up his sleeve to make that hang time seem longer. When he dunked, he held onto the ball a bit longer than most players, and actually placed it in the basket on the way down. He also pulled his legs up as the jump progressed so it appeared that he was jumping higher. But it still all happened in less than one second. Dancers can raise their legs during the jump to make it appear higher and more impressive.
The American Association of Physics Teachers and the American Physical Society contributed to the information contained in the TV portion of this report.