Do Humans Bounce?

[BigALP]

Now this does sound a bit morbid but it's genuinely something we've been trying to get to the bottom of. The question is simply "If you fall from a plane without a parachute and hit the earth, would you simply hit the ground and stop or would the impact force you to bounce if only a little?" We've tried devising a formula using height, acceleration, mass of body, surface area in impact and density of the ground but we're not sure. Anyone able to help. Again apols for the macabre nature of the question but it is a genuine one. We've tried to devise a formula

[ham]

hi i was going to ask this question i think its quite interesting i hope u find a answer!

[Francis Asis]

I beleive the answer to be No. My grandad worked as a building site manager and he told me once that someone fell off a high building and they had to dig him out of the ground.

[gerkin]

Devising a formula would probably not give you an accurate answer as you would have to make so may assumptions on the material properties of the human body. The problem is highly non linear as the body will not remain elastic during impact as breaking bones, snapping of tendons and crushing of fat and muscle(assuming height greater than 5 meters onto concrete) will absorb substantial amounts of Kinetic energy. The orientation of the body at impact will also play an important part e.g. if the body landed directly onto the head the head would dispear into the rib cage along with crushing of the skull, which would absorb a certain amount of energy. Other paramterers to consider are fat layers, bone brittleness (does the body suffer from osteoporosis) was the body dead or alive before impact (rigormortis will give a stiffer structure) The best ways however to get accurate results are:- 1) Testing - Drop a corpse out of a high window onto the pavement and film the impact. This will have to be done several times on fresh corpses to establish which impact orientation will lead to the highest bounce (if any) 2) Use Finite Element Analysis (FEA) to perform a dynamic impact analysis of a mathematical model of a body onto a rigid surface. Once the model is created (the hard part. i.e modelling bones and flesh) the FEA can be used to perform several analysis which varying impact orientations). Bra manufactures use FEA to model the female breast so the can predict dynamic support.

[bernardo]

It depends on the surface which they land on, and the position of the body when it impacts. There have been cases of babies surviving falls from high buildings because they were cushioned by their nappy etc. There would be some bounce in some cases, e.g. if someone falls intop a dens patch of vegetation or jungle in which case there would be a cushioning and elastic effect.

[bernardo]

Ha ha ha - I've just noticed the bit in your question about "trying to get to the bottom of" and my answer about the nappy!

[New Forester]

I think it was Thomas Huxley who explained the varying terminal velocities of bodies of different sizes by saying (something like) if you dropped a mouse down a mineshaft it would walk away. A rat would be killed, a human would smash, but a horse would splash.

[sddsddean]

Don't know if you have ever seen the footage of the US Airship Akron in the 1930's. This was visiting some air station or other and about 100 cadets ran out to grab the mooring lines. At that point the airship was caught by a draught and rose about 150 feet... with 3 of the cadets still holding on. 2 could not hold on and the camera followed them all the way to the ground. They didn't bounce.

[el duerino]

i have bounced off hard ground when playing sports. Presumably this is because my body could store enough elastic energy through the impact. however if it was a high fall then the elastic components would break, not rebound, so no I do not think a human would bounce from a high fall, but might from a small one.

[atkins]

i would say yes as i skateboard an i have thrown myself down a few big stairsets an i can definatley say yea humans do bounce