How can we see a bullet’s angular momentum?
Mythbusters tested this claim in episode 166 – “Spy Car 2”, May 18, 2011
Myth Statement: A bullet fired into the surface of a frozen lake can spin like a top on impact. Inspired by a viral video.
How does a bullet start spinning to begin with?
Guns are rifled in order to impart spin to a bullet leaving the barrel.
Rifling gives the bullet angular momentum, which stabilizes it
(keeps it from tumbling)
A sudden decision to aim a handgun at some Houston County ice in 2003 yielded a video of spinning bullets that became an Internet sensation and led to a May 18 appearance on cable television’s “Mythbusters” show. The “myth” was born on a winter afternoon when Nate Smith of La Crescent, Minn., along with friends Nate and Andy Van Loon, were shooting bullets from a 9-mm Glock from a hillside toward a patch of ice on the Van Loons’ land near Houston.
“We just went out, not being very smart, and were shooting the ice and watching the pieces of ice fly, and we were recording ourselves,” Smith said. “I remember, after we shot a couple times, wondering what that crackling sound we were hearing was.”
After firing multiple shots, they found the bullets spinning on end on the ice surface, a few feet back from the point of impact. “You could see the trail from where it ricocheted and that’s how we found it,” Smith said. “And it went for about two minutes, so we just filmed that.”
The only explanation Smith could offer is rifling in the gun barrel caused the bullets to spin. Though Smith first put the video on the Internet in 2005, it took off in December 2009 when Smith’s friend Jason Nesbit asked if he could re-post it on YouTube. More than a half-million people have since viewed it.
When questions arose over the validity of the clip, Nesbit asked if he could re-create it on a local frozen lake. “We didn’t think anything would happen, so we said, ‘Sure, go ahead. Do whatever,'” Smith said. But Nesbit went further, sending the video to the “Mythbusters” website, where it caught the attention of the Discovery Channel show’s producers. Smith and Nesbit also were contacted by an Asian television show that paid them a small stipend to use the video. Smith watched May 18 as the “Mythbusters” hosts worked to prove or disprove what he had seen with his own eyes. “Somehow, they get their bullets to just spin like a top,” host Kari Byron said on the show. “Now that sounds like a myth,” co-host Tory Belleci added.
The key element was finding the correct angle to fire the gun into the ice, Belleci said. Too straight would deform the bullet too much to spin, too shallow would send the slug skipping off the ice.
The hosts set up nine 40-by-24-by-10-inch chunks of ice next to each other to replicate the frozen lake. The first shots became embedded in the ice and had no chance to spin. But a bullet was recovered that hadn’t deformed, a cause for cautious optimism. Yet the next several tests failed to yielded a spinning bullet, so the hosts tried firing at an angle to ricochet off a large piece of ice between 2 and 8 feet away from the initial contact point. The hit was clean, but the bullet was gone. Several more tries, several more lost bullets. The hosts decided to try again six months later on an actual frozen lake. But shot after shot and no luck. “This myth sucks,” Belleci said in the blizzard-like conditions.
For the final test, they gave the bullet room to ricochet backwards, as it had on Smith’s outing. After countless attempts, they found the spin they were looking for. It happened again and again, confirming the myth. Smith said the whole experience was somewhat surreal, since he once joked the video might someday make it to “Mythbusters.” “Eight years later, here we are and it was on TV,” he said. But he doesn’t recommend anyone try this at home. “Looking back at it,” he said, “it wasn’t very safe.”
- article from Lacrosse tribune. ‘Mythbusters’ tackles Houston County video of spinning bullets. By Ryan Henry, Houston County News
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