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Re: Henry LaMothe



I mistyped. LaMothe continued until his 70's.

If one falls onto one's back, the threshold for survivability (see
reference below) is a force of about 27,000 pounds = 1.2 x 10^5 N.
This means an acceleration of near 140 g. There are numerous cases of
people falling from airplanes without parachutes and surviving by
landing in snow, or hitting an evergreen's boughs and then a
hillside. This is a great example to use when discussing impulse and
momentum.

In WW2 the Soviets even experimented with dropping combat troops from
low flying airplanes into snow from heights of 15 to 50 feet. "About
half of the men dropped were still able to fight and the experiments
were soon abandoned."

"Terminal Velocity Impacts into Snow", R.G.Snyder, Military Medicine
131, 1290-1298 (1966)

quoted in "Physics with illustrative examples from medicine and
biology, Vol 1 Mechanics, George Benedek and Felix Villars, Addison
Wesley (1973).

>This is in the 6th edition ofHalliday, Resnick,
Walker Fundamentals. They give height as 30 m,
water depth as 30 cm and say that M. LaMothe did
his act until he was in his 90's.

This sounds incredible. Whatever speed he reaches in the fall he has to
loose again in the tub, so v^2 = 2 a(1) x(1) = 2 a(2) x(2) , or

a(2) = g x(1)/x(2) = g 30m/0.3m = 100 g

So his average acceleration is 100 g during the stop. Is that survivable?
He's going from 90 km/hr to 0 in 0.025 s!


Tim

--
Dr. Vern Lindberg 716-475-2546
Department of Physics Fax 475-5766
85 Lomb Memorial Drive
Rochester Institute of Technology Computer Haiku
Rochester, NY 14623
A file that big?
It might be very useful.
But now it is gone.