I was watching Sport Science the other day and they stated that a human cannot jump up and stay in the air as long as a second. This astounds me. Not even a second? Does anyone know if this is true?
They were talking about:
Taking off from a level, hard surface
Jumping from feet and landing back on feet
Earth gravity
A standing vertical jump or a long jump?
I’d say some of the jumps performed by this guy must be getting close (I know some of them are in slow motion, so don’t count.
Let’s define flight. From Wiki:
A human cannot aerodynamically generate lift or aerostatically use buoyancy in air. Maybe underwater with full lungs, but not in air.
Nope, not even for one second.
We might be able to glide a bit in a really strong wind or for instance when jumping out of an airplane, but no, we can’t achieve flight as it’s generally understood. Even skydivers can’t generate lift, although if I’m mistaken on that someone will surely correct me soon.
The Hyper-Physics site at Georgia Tech tells me that to attain a vertical airtime of 1 full second, a person would have to have a vertical launch velocity of almost 11 miles per hour, and have the bottoms of their feet reach just over 4 feet off the ground at the peak of flight.
Those would have to be some serious thigh muscles.
Let’s not get hung up on semantics - it’s pretty clear that the OP is just talking about jumping, not actual flying.
Do the math. d = 1/2 a t**2. a = 32 feet/second/second.
Assume symmetry – if it take 1/2 second to fall, it also takes 1/2 second to jump to the height that would allow you to be in the air for one second. So, d = 4 feet? The world high jump record is a bit over 8 feet. So…unless my math is wrong somehow, it seems like a dubious factoid.
You may be able to quibble about center of gravities or something like that – by the time that the jumper’s legs are over the bar, the rest of them is halfway down to the mat.
I found the formula for projectile motion and the world record for the high jump (2.45 meters). I think what you want to do is solve for t and assume a stationary object dropped from 2.45 meters, and then multiply by 2 to get the total air time.
So if we subtract the time our jumper is ascending and descending, can a human hover at the peak of her jump for over a second?
Why? The OP’s question seems pretty clear, even if it doesn’t fit the definition of ‘flight’ you’d prefer it were using.
If I’m correct the world record high jump has an air time of 1.4 seconds.
I’m almost certain this also isn’t what the OP meant. Are you doing this on purpose?
For a high jump of height X, the jumper’s center of mass is actually elevated by an amount significantly less than X, for at least two reasons:[ul][li]It didn’t start from the ground - a standing person’s center of mass is, what, three feet off the ground or so? Possibly more, depending on height?[*]If the Fosbury Flop technique is used, the jumper’s center of mass can pass below the bar as he curves around it - by as much as 20 centimeters, according to Wikipedia’s article.[/ul]Although it must be possible to increase one’s hang time by either curling one’s legs or, even better, rotating so as to land flat on one’s back or stomach. You won’t go any higher , but you’ll fall farther before hitting the ground - your center of mass will be a few feet lower than it was when you started.[/li]
I’m not brave enough to try that on a gymnasium floor, though. Ouch.
So in that case, the centre of mass would have moved about 5 feet, or ascended about 3ft and fallen further onto the mat. This seems fair enough for a bar set at 8ft, bearing in mind the fosbury flop means the centre of mass can remain below the bar. Someone else can do the accurate maths 
Edit: too slow
Um, that ain’t how physics works, even if that’s what coyotes going off cliffs do. The leaper’s center of gravity describes a parabola, constantly rising but at a decreasing rate, until reaching an apex with zero velocity for an infinitesimal moment (NOT “hovering”), then the CG falls at an increasing rate.
But the CG is within the top 1/4 of the vertical travel for half the total time of the leap, moving at a very slow speed, and can almost appear to be hovering. The movement of the arms and legs can thereby create the illusion of “hang time”, but the torso is actually still rising and falling.
The high jump is achieved using a pole-vault right? Not quite the same thing as jumping. I’ve never heard of anybody with a vertical jump of more than 50 inches.
I think levdrakon is trying to make the point that an object in freefall is not strictly in ‘flight’. In which case, of course, we must also refuse to talk about the ‘flight’ of a golf ball.
Ummmmm…in the pole vault competition, yes 
The high jump is a jump.
I’m really not sure what levdrakon is doing - I mean, I know we’re famed for our semantic nitpicks here at the dope, but this one is just altogether too strenuous.
That’s right. Also, the Shot Put consists of throwing a discus or javelin.