Olympics flashbacks: The physics of a Michael Jordan dunk
Why Jordan's hang time seemingly defies gravity.
In 1992, the world met the Dream Team. They were, as coach Chuck Daly put it, "like Elvis and the Beatles put together" — twelve rock stars who took home the gold with ease. At the Barcelona Olympics, the US beat eight teams, with world-class athletes of their own, by an average of 44 points.
It was also the first Olympics to include NBA players, a squad that included Magic Johnson as point guard, Patrick Ewing as center, and Karl Malone as power forward. And then — there was Michael Jordan and his dunks.
While we wait for the 2021 Tokyo Olympics, Inverse is looking back on past Olympic moments and celebrating the science of sports.
The Olympic moment: The 1992 Barcelona Olympics were also the first games where there were no tryouts for the basketball team. The roster was chosen by a committee that spent two years carefully putting together a high-performing squad that would still like each other at the end of the day.
It was a team of stars, with Jordan shining the brightest. He was the Dream Team's highest scorer with 14.9 points per game and made a tournament-high 37 steals. When Jordan dunked "that's what people had been waiting for" — fans from around the world flocked to see the Dream Team play, eager to see if the hype was real.
A set of two dunks by Jordan in a 1992 Olympics Qualification Americas Tournament Game against Argentina.
You can also watch the entirety of the Dream Team's first Olympic game below:
USA vs Angola, 1992 Olympics.
The science: What makes Jordan's dunks so infamous is his hang time. Hang time is the total time that an object, or a person, stays in the air after leaving the ground. It's measured from the moment something leaves the ground until it is back. An average human's hang time is about 0.53 seconds. Jordan's record is 0.92 seconds. That's why they call him His Airness.
Why is may seem like Jordan is breaking the laws of physics, we can actually use that scientific discipline to make sense of his soaring.
Duane Knudson is a professor of biomechanics in the Department of Health and Human Performance at Texas State University. He tells Inverse that a person's time in the air is a function of three parameters:
- The height of the center of mass of the body (CM) at take-off
- Vertical velocity at take-off
- The height of CM
The CM is the point where an object's mass is equally distributed in all directions. Where it is on a person typically depends on the sex, but when one is standing straight and still, it is typically near the top of the hip bones.
The maximum hang time a person can achieve is 1 second — so a bit higher than Jordan's record. Knudson explains that the visual illusion of extra hang time you might associate with Jordan is really just a function of a running jump.
"The flight path of the body CM is always a flat parabola, just like the laws of physics say," he says.
Because athletes move their arms and legs around, their CM moves within the body. Our eyes track what's seemingly following a flatter path — parts like the trunk or the head — while the whole body CM continues to follow a flat, parabolic path. Meanwhile, coordinated limb movement can help athletes who want to improve their hang time stay in the air longer.
"Jordan or any current athletes with great jumping ability just jumps higher, and if they take-off a little higher and land a little lower on a running jump, it just appears they hang in the air," Knudson explains. "The extra time is really a function of jump height, a high position at take-off, and perhaps a bit lower, [flexed] landing position."
It's either that, or it's his shoes.
