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LESTER HOLT, anchor: As athletes push themselves to their limits
and sometimes crash or collide, they rely on protective gear to keep them safe.
Two materials science researchers funded by the National Science
Foundation, Cornell's Melissa Hines and Ohio State's Kathy Flores,
explain the physics of a collision and exactly how this equipment,
especially the safety helmet, works to prevent injury.
HOLT: Winter Olympic sports are high-speed, high-intensity, high-impact.
These sports are not only thrilling--they're dangerous.
In 2008, two-time Olympian Scott Macartney took a spectacular fall
while competing in the downhill in Kitzbuehel, Austria,
slamming to the ground at almost 90 miles per hour.
Mr. SCOTT MACARTNEY (U.S. Ski Team- Downhill): It was a tough crash,
a big concussion, and took a lot to overcome that.
Ski racing is a dangerous sport, and injuries are part of that.
HOLT: To prevent injury, most Winter Olympic athletes wear some kind of
safety gear--padding, shin guards, gloves, safety glasses.
But the single most important piece of protective equipment in these
Games is one familiar to anyone who rides a bicycle: the safety helmet.
Julie Chu is a forward on the US hockey team, who won
silver and bronze medals in the 2002 and 2006 Olympics.
Ms. JULIE CHU (U.S. Hockey Team): The helmets these days are really high tech
and sophisticated, and they're really well padded.
Inside you'll see kind of like the thick foam in there, um, and this
will kind of help us be able to absorb a lot of that impact that we do feel.
HOLT: And dissipate energy. Anything that's moving has energy.
When that moving object collides with something,
that energy has to go somewhere.
In what's known as an "elastic collision"--say, between two curling stones --
the energy in the moving stone, called kinetic energy, is transferred to
the stone at rest, causing it to move.
But what happens when a soft object--like a speeding Scott Macartney's head --
collides with the frozen ground?
That's an inelastic collision.
Some of the kinetic energy can be transferred into breaking the skull,
shaking--crushing--the brain.
But that's where the helmet comes in.
Although it shattered in the crash, Macartney's helmet absorbed
much of the first impact.
Dr. KATHARINE FLORES (The Ohio State University): Essentially a safety
helmet is intended to take the impact and distribute it, uh,
so that rather than all of the energy going into the skull,
or into the brain, it distributes the energy around a larger area.
Dr. MELISSA HINES (Cornell University) All of the helmets start
with a hard outer casing like this.
If you have something that comes in and hits your head like this,
instead of having the force just in one location, the hard protective shell
spreads the force out over a larger region.
It diffuses the force, diffuses the energy.
HOLT: The foam lining of the helmet helps absorb the kinetic energy.
Dr. HINES: The really important part is when you look inside
and when you look at the foam.
It's this inner liner here that's going to absorb the energy of the impact.
If I was to look at it in one of the high-tech microscopes we have here,
what you would see is it looks exactly like very small bubble wrap.
HOLT: Which Prof. Melissa Hines, Director of the Cornell University Center for
Materials Research, says, is a good way to show how most all safety helmets work.
Dr. HINES: When you have an impact--so something comes in
and hits the foam like this--the energy of the impact can actually
be absorbed by the bubbles.
As you push down like this, the little bubbles start to pop.
Every time one of these little bubbles pops,
what you do is you absorb a little bit of energy.
And so you can take the energy, say, from your head hitting a tree,
and you can absorb it in the foam and not absorb it in your skull.
HOLT: The same way energy in a car collision is absorbed when a car
hood crumples or a fender is crushed.
Dr. FLORES: That's where you're absorbing all your energy,
is as the foam is crushing.
HOLT: You can see that in an impact test Professor Kathy Flores did on a
hockey helmet in the materials science lab at Ohio State.
Dr. FLORES: What we saw mostly was that this outer shell had been
dented, and we could see that the foam itself was also compressed a
little bit--you can see that it's a little thinner here than it is
on the side that wasn't impacted.
The helmet was pretty much doing its job.
The foam is compressing and absorbing the energy of the impact.
Almost all protective gear these days is made out of a foam.
HOLT: Materials scientists and chemists engineer other properties
into Winter Olympic safety helmets: they have to be light weight,
to not strain the neck, able to withstand cold temperatures,
and other hazards on the snow and ice.
Mr. MACARTNEY: My helmet has a Kevlar shell around the outside that
protects against not only impact but things going through the helmet.
Dr. FLORES: In some cases, you're more worried about the helmet getting slashed.
You might be trying to protect against the slash of a hockey blade,
versus an impact of a bobsled helmet against the side.
Ms. CHU: The helmet's one of the key pieces of equipment for us.
Our brain's pretty important; we want to take care of it.
HOLT: For these Olympic athletes, the safety helmet is critical
to keeping their head in the game.