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Episode 47: Catching a Bullet with Your Teeth and Helium Footballs

  • Helium-filled footballs travel farther: mythbusted (they might even travel less far)
  • Catching a bullet with your teeth: mythbusted (a no brainer, but more interesting for their attempt to mechanically catch a bullet)

This episode featured slow-motion shots of a pig's head being shot. To quote Kari, "That is probably one of the most disgusting things I have ever seen and I'm trying to stay in my happy place."

FYI: even though they advertised "Season Two DVDs now available" during the show, the Discovery Channel Web site is still selling the 13 DVD version of the set that's twice as expensive as Season One. They eventually repackaged Season One down to 4 DVDs and slashed the price to $50, so I'm still waiting for the same with Season Two (both seasons are the same length).

Helium Football

Myth: Helium-filled footballs travel farther than regulation footballs

Irrelevant stat from this myth: they filled up a football to find out that at 110 psi a football will explode.

Possible source of myth

Ray Guy, punter for the Oakland Raiders from 1973-86. His punts stayed in the air so long that they invented the hangtime statistic for him. In a game against the Houston Oilers, he kicked it so well that the opposing team collected the ball and tested it. There was no helium.

Testing with an actual punter

They went to City College of San Francisco and got Tim Sonnenberg, punter, to kick some footballs for them. Tim first demonstrated the two types of kicks used in football:

  • kickoff: end-over-end. Maximizes hangtime and makes it harder to catch.
  • punt: impart spin on ball with foot to make it spin. Maximizes distance and accuracy. Spiral allows it to travel farther.

Jamie and Adam took their shot at kicking (Jamie's kick was rather sad).

Jamie: "Football's not my sport. In fact, there aren't really aren't any sports that are mine"

Tim Sonnenberg: "I believe helium would add a good 5-10 yards to a good kick"

They filled up footballs to 13 psi and had Tim take five kicks with the air-filled and five kicks with the helium-filled. They used the same footballs for each set, refilling them in-between. Attempting to read Adam's handwriting, the data appears to have been 47, 53, 41, 34 (37?), 46 for the air-filled footballs and 41, 54, 56, 43, ? for the helium-filled.

Tim incorrectly thought the first set of balls were helium. Despite Tim's bad guess, the helium-filled balls traveled three yards farther on average. However, they only took five data points per ball and there kick-to-kick variations of close to 20 yards.

Measuring the weight of footballs

Adam and Jamie decided to actually weigh footballs to find out what the difference between air-filled and helium-filled footballs. They took their balls and weighed them both empty and full of air/helium. They found out that: * air in a football weighs about 3.2 grams. * helium-filled footballs are 7 grams lighter than an air-filled one. * helium-filled footballs are lighter than an empty football by about 1%.

Helium is only half as dense as air.

Launch test

In order to get more consistent results they went for consistent 'kicking' and consistent weather. For the final test they got a football launching machine and went to one of the old blimp hangers at Moffett Field (230 ft high, almost a quarter of a mile long).

They fired twenty air-filled balls and twenty helium-filled balls and got more consistent results than with the punter. Rather than showing the helium balls traveling farther, if anything, the air-filled balls had a slight advantage. (NOTE :The announcer claimed that they had 60 data points, so I'm not sure what the missing twenty data points are.)

Surprisingly, the MythBusters actually went to an actual statistician to analyze the results instead of doing their own, usually poor, analysis. Deborah Nolan, Professor of Statistics at Berkeley, decided that the final results showed that there was no statistically difference between helium-filled and air-filled balls. From the test data, there was about a 1" advantage for the air-filled balls over 70 yards.

Springiness test

They tested one final theory with the balls: springiness. They wanted to see if helium-filled footballs would receive the energy of a punter's kick better. They swung a sledgehammer pendulum into a football and measured the speed of the ball using a high-speed camera. The speeds were the same.

The short explanation: it's not about weight, it's about pushing through the air.

The physics explanation: the heavier the object, the greater the inertia. An air-filled ball has greater inertia flying through the air, which reduces it's drag.

mythbusted

Catching a Bullet in Your Teeth

Myth: You can catch a bullet that's fired at you in your teeth

They showed a clip from a 1952 TV show, You Asked for It, that shows a person catching a bullet with his teeth.

Teeth strength test

The build team created a teeth/jaw strength test using dentures, a bullet, a pendulum, and a metal pin. A 50 lb. pendulum swung down from a height of 4 ft, struck a metal pin, which then struck a bullet held in place by the dentures. The height and weight of the pendulum were calibrated to deliver the same amount of force as a bullet and the dentures were calibrated to have the same bite strength as Tory's.

Test 1 (Bullet held with front teeth): Knocked the two front teeth loose

Test 2 (Bullet in back of mouth): The mouth held on with some chipped teeth here and there.

Reaction time test

The build team wanted to see if was even possible for a person to react quickly enough to a bullet firing to close their mouth around it. Tory fired a blanks from a pistol and Grant and Kari closed their mouths in response. Kari's reaction time was fasted at 9ms when a countdown was given.

Paintball catching test

The build team figured that catching a paintball had to be easier than catching a bullet, so Tory fired paintball bullets from 25 ft at Kari to see if she could catch them. Kari didn't even come close as Tory fired paintball after paintball.

Pig jaw and teeth test

They weren't sure that the denture test was accurate. Tory collected some pig jaws so that they could use some real teeth, with the logic that a pig's jaw is stronger than a human's jaw, so if a pig's jaw couldn't do it, neither could a human's.

Kari: "Can we find a story where we don't work in dead animals. For real."

Tory: "Kari, did you want the snout, because I was going to throw it away --"
Kari: "That is probably one of the most disgusting things I have ever seen and I'm trying to stay in my happy place."

Tory ran a cylinder through the pig jaw so he could clamp it down.

The pig jaw didn't hold onto the bullet when they dropped the pendulum (50 lbs from a height of 4 ft).

Next, they fired a .357 magnum with .38 wadcutter round into another bullet held in the pig's teeth. The bullet destroyed the teeth in the mouth.

Metal Jaw test

Grant built a rig to try and catch a bullet traveling 857 ft/s. A gun was setup at one end and pneumatic metal jaws at the other end (25 ft away). A signal was sent when the bullet was fired so that the metal jaws could be triggered to close at the exact right moment. Grant's electronic timer could be tuned to the nearest millisecond. They went to the South San Francisco Police Department firing range where Sgt. Alan Normandy (who helped in the Blown Away myth) helped them out.

Metal jaws: it took several shots to catch a bullet. In some cases the bullet struck off the front as the jaws closed too soon, in others the jaws were just too late. They used the high-speed camera to fine-tune the jaw timing but still could not catch a bullet.

Metal duckbill: they switched out the metal jaws and replaced them with something that was more duckbill-like so that there would be more surface area to catch the bullet. It took six shots, but they finally 'caught' a bullet. Mostly they caught a small metal smear of lead as the rest of the bullet exploded away.

They switched to a full metal jacket bullet to see if they could catch a more intact bullet, but still ended up with a smear of lead. Even with electronic timers it took multiple attempts to catch a bullet and the bullets they caught were smeary fragments.

To close things up they took a shot at a set of dentures and blew up the upper half. Kari got hit in the face by shattered denture debris.

mythbusted

Comments

I'm sure you have researched this.I saw how the bullet catch was performed. ths link isn't exactly the way i saw but is similar.
http://www.reference.com/browse/wiki/Bullet_catch

If the helium ball weighed 7 grams less, is should have flown 3.5 feet more over 210 feet if they had applied an equal amount of energy to the ba11s instead of launching them with an equal velocity. Anything launched with a certain velocity at a given angle will travel the same distance no mater what the weight...d=v^2sin(2theta)/g...the myth isn't busted because they didn't similate a real arm that will add a more equal amount of force times distance (energy) to the balls.

I have heard about a Marine in Iraq who didn't exactly catch a bullet with his teeth, but two or three of his front teeth were knocked out by a bullet fired from a pistol at nearly point blank range and the bullet perportedly stopped, taking the place of the teeth. Is there any truth to this story? And if so, How can that be explained?

@scott: But only if you are in outer space, Scotty! Or can you throw a party balloon like a football on planet earth? It's busted!

@Robert Anderson: No, it is not true - it's just another myth.

The lighter football definitely could perform better if spin was imparted, they didn't test for that, so I think under certain conditions the helium would DEFINITELY improve the balls performance. Especially in game-like conditions, the helium would improve performance, due to spin factoring in, density of ball is approx constant, thus the lift of the helium reduces the weight of ball by 7 gms, that's significant.

7 grams will get you ten years, if it's a drug!! it will surely affect a football!!

The story about the soldier in Iraq getting shot in the face and being saved by his front tooth is true.

http://www.snopes.com/photos/military/teeth.asp

It has been argued that the lighter the football is, the further it will fly. Try a very simple experiment. Tape a piece of paper around a 1" rock and throw it. Measure how far it flies.

Then, take a 1" wad of paper. Tape another piece of paper around it, and throw it. Measure how far it flies.

Which one do you think will fly further? Yeah, without trying you know that the rock will fly further.

Why? Because the momentum (mass times velocity) is what keeps the object moving forward, while the drag (the force of the air caused by the speed of the object) makes it slow down.

The drag for both is about the same, but the lack of momentum of the lighter object would make it slow down more.

The analogy to the football is not perfect. However, the energy put into the ball by the kick will be about the same. After that, drag (or friction) will take over.