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).
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.
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.
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.
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.