A pertinent question to ask as we approach New Years’ Eve. The answer is, as is so many things, “it’s complicated.” According to the Straight Dope, the answer is “it depends.”
When an object falls, there are two main forces on it — gravity, and air resistance. Air resistance depends on how fast something is moving, so the faster the bullet goes, the more air resistance. So at a certain point, the forces of gravity and air resistance are in balance, and the bullet falls at a constant speed (since you need a net force in order to accelerate, or increase your speed). That’s called terminal velocity.
So, is the terminal velocity of a bullet fast enough so it has enough energy to penetrate the skin? Snopes reports that, back in the 1960’s, the army determined that the energy in a 0.30 caliber bullet falling from the air was about half that needed to produce a disabling wound. Case closed? Not quite. For one, different bullets have different terminal velocities AND different bullets require different speeds to penetrate the skin.
This is the only “Mythbusters” Myth to be rated both “plausible, confirmed, and busted” at once. If the bullet is fired straight up, it tumbles and falls at terminal velocity, they write.
But that’s not how bullets are fired, most are fired at a shallow angle. That’s why, in most news reports of victims of falling bullets, the victim is pretty far from the shooter. If the bullet is shot at a shallow angle, it doesn’t tumble, and can pack a hefty wallop — much faster than terminal velocity.
Conclusion: If you’re stupid and shooting on New Year’s — at least use a protractor. Fire at a 90 degree angle to the ground. If you’re shooting at a shallow angle, you might kill someone.
Of course, we’d all be safe if people just stuck to the old tradition of firing shotguns with pellets. Birdshot doesn’t have good ballistics — the bullets don’t spin cleanly, thus achieving the high velocities of bullets. You’d just be showered with pellets, as if they were tossed in the air.
For the mathematically inclined, here is a detailed description by high school teacher Roy Mayeda:
As to the speed at which the bullet leaves the barrel (muzzle velocity), a REALLY SLOW bullet would do 500 mph (733 ft/s), like a light 38 Special target load or light 45 Auto. The little old 22 Long Rifle high-velocity (“normal”) averages around 1200 ft/s (818 mph). Typical 357 Magnum defense/police load leaves at about 1450 ft/s (988 mph), .30-06 Springfield at about 2900 ft/s (1977 mph), one of the new hot-rod varmint cartridges, the 204 Ruger has a factory load listed at 4225 ft/s (2880 mph). As a rule, mainly older, lower-powered cartridges fire bullets with subsonic speeds, though the best competition-type 22 rimfire (22 Long Rifle) cartridges are also subsonic — avoids bullet experiencing turbulence that a supersonic projectile would encounter as it dropped to subsonic speed. For maximum accuracy, it’s usually recommended to keep the projectile either supersonic or subsonic for the entire flight, rather than letting it drop through transition speeds.
One of the first photograps of the bullet in flight made by Peter Salcher with Ernest Mach in 1886
I am a science education and communications consultant -- view my website for my full range of services.
I’m recently enamored with the blog from ASSETT (Arts & Sciences Support of Education through Technology) at the University of Colorado — they have great short posts on different technology tid-bits for use in the classroom.
Recently, they’ve had a selection of science blogs, along with detailed synposes of what you’ll find on each blog.
One of the things that’s puzzling to anyone, and especially us logic-oriented scientists, is how people can look at strong evidence and seemingly ignore it. They go with their gut, or what they think they know, instead of the data staring them in the face.
This is the basis of a huge amount of work in what is called behavioral economics — or, the psychology of why we make the economic decisions that we do. There’s a great article and radio piece on NPR about Daniel Kahneman’s work in economics, which won him the Nobel Prize in 2002. For instance, we have the illusion of validity (we have too much confidence in our own judgment), or the anchoring effect (we’re unduly influenced by numbers that we’re exposed to, such as a “compare to” price on an item).
Here are some classic examples, as written in an email from Nathan Lasry:
1- A group is given the price of an object they must buy. The same object can be purchased 5$ cheaper across town (remember this is 5$ in the late 70s early 80s, so was worth much more than today’s 5$). The question: Would you drive across town to get the object?
Most people said YES to driving across town IF they were saving 5$ on a 15$ calculator.
Most people said NO to driving across town IF they were saving 5$ on a 125$ coat.
The trouble? When you walk into the grocery store to spend that 5$, it really doesn’t matter where it came from…
This result does not fit at all with classical economic theory that portrays humans as ’spock-like’ rational agents that would place an absolute value on driving across town.
2- In another interesting example, people were asked:
Do you prefer getting $1000 with 100% certainty or getting a 50% chance of receiving $2500. Most will choose the certain $1000, although the expectation value of the second option is higher 1250$. This is ok from a strictly rational perspective because these folks are willing to pay 250$ as ‘insurance’. So you can call them ‘Risk aversive’.
BUT
The same people are then asked what they would choose between a certain loss of $1000 versus a 50% chance of either loosing nothing or loosing $2500. Most will choose the riskier 50% alternative. So the SAME ‘risk averse’ people in the first example become ‘risk seeking’ in the second.
These, and all sorts of other biases, are outlined in a great book I’m listening to right now, How We Decide. A lot of the themes from this book keep cropping up in my favorite podcast, Radio Lab, especially their recent episode on Choice. If you find this stuff interesting, check out the work of Baba Shiv, who sticks his subjects into MRI machines to see the hardwiring underlying how emotions affect our decisions. He was the one who did the famous study showing that people not only rated the same wine more highly when told it was expensive, but actually had a better subjective experience of the wine based on their expectations. And here is a TED talk by Dan Ariely on how our irrationality is predictable, and we can be encouraged or discouraged from cheating with some simple manipulations, like being reminded of an honor code, or replacing cokes with dollars. He calls this our “buggy moral code.”
- halo effect: attractive people are seen as better teachers, they earn more, etc. (presumably halos from non-people have an impact too)
- priming: what is in your mind when a second topic comes up is likely to color how you view or judge the second. Marcus gives this example: you ask undergrads how happy they are and how many dates they had last month. If the happiness question is asked first, there is no correlation between the answers. If if you first ask about dates, there is a correlation between the answers.
- anchoring and adjustment (a variation on priming): a number that people have in mind influences their estimate of something entirely different. One example: add 400 to the last three digits of your phone
number. Then, when did Attila the Hun’s rampage end? If the phone answer was less than 600, the median guess was A.D. 629, if the sum was between 1,200 and 1,399, the median year was A.D. 979.
- mere familiarity: people prefer what they know. Marcus reports one study (now done in 12 languages) that people prefer letters in their own names. One study told half the participants that feeding alley cats were legal and the other half were told it was illegal. Yet, most favored the current policy, whichever it might be.
- threat: the more we are threatened, the more we cling to our beliefs. I could imagine that this comes up in the physics classroom when beliefs about mechanics are challenged.
- confirmation bias: we tend to be place more weight on evidence that supports our beliefs than evidence that doesn’t (I think this one is widely known); the flip side is “motivated reasoning.”
This examination of the irrationality of people’s economic behavior was apparently pretty controversial stuff in economics, whose models assumed that humans are essentially rational and logical decision makers who will make the choices that benefit them the most.
But there’s probably another reason for economists’ resistance. An imperfectly rational human being challenges a really important idea: the notion that markets work well because individuals can be counted on to make the best choice for themselves.
“Merely accepting the fact that people do not necessarily make the best decisions for themselves is politically very explosive. The moment that you admit that, you have to start protecting people,” Kahneman says.
In other words, if the human brain is hard-wired to make serious errors, that implies all kinds of things about the need for regulation and protection.
In our own work in educational research and reform, this has many implications as well. After all, we’re often presenting faculty with data and information at how students learn best, and meeting great resistance.
I am a science education and communications consultant -- view my website for my full range of services.
The National Association of Science Writers has a nice news feed now (check it out at http://www.nasw.org/, though the RSS feed isn’t obvious — ask me if you want it). So, here I’m reposted a repost of a Wired article on Five Atrocious Science Cliche’s. Think that it’s time that we found a silver bullet for all the Holy Grailsthat scientists seem to always be seeking? This article will shed some light on all the missing links that will eventually lead to a paradigm shift in modern science.
Look, we found the missing link!
Other posts include information on the Freedom of Information act, science news roundups, and articles on the future of science journalism.
I find the argument against science cliche’s very interesting, as a writer myself. The problem with a bunch of these cliche’s is that they’re often misleading. “Missing link” for example, is an overused phrase that suggests that our models are so clean and tidy that if we find one missing piece, then it fills in the rest of the story. “Holy Grail” similarly misleads people about the nature of science…. with very few exceptions (e.g., the Higgs boson) there are very few things that scientists are searching for as a perfect shining goal.
But of equal importance is that these cliche’s are just lazy writing. They’re shortcuts to a common cultural parlance, that let a writer get away from really describing what happened, of telling the story. They’re not universally demonic, but generally, they’re not helping to illuminate (shed some light?) on the science that is the subject of the study.
I’ve got a new podcast posted, this one with my esteemed colleague Valerie Otero of the University of Colorado at Boulder. She tells us why she thinks that the idea of student “misconceptions” is very dangerous — and gives us a new way to think about student ideas in the classroom, and some activities to address them. This is in the Beyond Penguins and Polar Bears episode on Keeping Warm, and targets common student ideas about heat. Still, the general message about misconceptions is, I think, one that every teacher should hear.
Got a geek in your life who’s aching for something cool? Here are a few ideas:
Giant Microbes are always a hit. Many years ago, my housemate gave me the common cold. I eventually gave it to my boyfriend (now my ex). No word yet on whether he’s recovered. At least I didn’t give him ebola. Now Giant Microbes even has bird flu and swine flu…
Made with Molecules This is the business of a wonderful science writer, Raven Hanna — silver jewelry in the shape of molecules . She’ll send you caffeine (for the coffee addict), serotonin (when you’re feeling blue), oxytocin (for valentine’s day)… they’re really lovely! If anybody’s looking for a gift for me, I love the serotonin necklace or earrings…
Trilobite For the bio-inspired, this site has clothing centered on evolution and paleontology.
XKCD.com has wonderful stuff inspired by the comic – posters, t-shirts, a tie, and more. The shirt to the left is one of my favorite items in my closet. Deadline for holiday orders is Dec 14!
Got a geek reader? Try a subscription to Isotope(a journal of literary nature and science writing) or Science News(all the news from the science world you could ever want in succinct well-written form).
And Sarah over at Schooner of Science beat me to the punch with her own geek shopping list, which is suitable for biologists, like cool lab coats and a tie, and my favorite, a cute bacteria wall clock.
I am a science education and communications consultant -- view my website for my full range of services.
I am a physicist, writer, podcaster, and educator in Boulder, CO. On this blog I get to wax on about science stuff I think is cool (like weird science, or stuff we think is true but isn't), K-16 science education, hands-on science activities, teaching pedagogy, and how to communicate science. Geek on. 8-)
. A lot of the themes from this book keep cropping up in my favorite podcast, Radio Lab, especially their recent episode on 
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