PZ notes and article about a controversial physics demonstration:
Every year, physics teacher David Lapp brings his Korean War era M-1 carbine to school, fires a shot into a block of wood and instructs his students to calculate the velocity of the bullet.
It is a popular experiment at Mill Valley’s Tamalpais High School, where students are exposed to several unique stunts that Lapp performs in his five classes every year to illustrate inertia, velocity and other complex formulae.
Turns out, it also may be illegal.
The legal problem is due to laws that were passed as an over-reaction to the high-profile school shooting incidents of the mid-1990’s. Which is a shame, because the “ballistic pendulum” experiment is a really cool example of physics in action. You can do it with low-velocity sping-powered projectile launchers (we sometimes do this lab in our intro class), but it’s just not the same.
Of course, Lapp is a piker. Back in my day, we did this as a lab in college– every student in the class got to personally fire a .22 rifle into a block of wood, and calculate the speed of the bullet. We even let pre-meds pull the trigger in a class I TA’ed, and let me tell you, there are few things as funny as a room full of tightly wound future doctors being startled by a gun going off (I warned them, but they didn’t believe me…).
It’s a great demonstration, and it’ll be a real shame if the experiment gets outlawed due to parental paranoia.
I don’t think children should be allowed near loaded firearms. Sorry.
How may spotted owls went home hungry because a huge forest was clear cut to make your wood bobs? Did the rounds contain toxic lead or barium and if so, were they disposed of in an EPA-approved manner? Was the area delineated by tiger striping plus red strobes at the corners and a klaxon during live fire? Did everybody wear eye and ear protection? Were students offered a non-violent computer simulation alternative? Were an equal number of boys and girls in attendance? How many Blacks were in the class? Were there accommodations for amputees, quadruplegics, and the blind to fire the weaponry?
Was there trauma counseling afterward?
Marine artillery brings dignity to what would otherwise be a vulgar brawl.
I don’t think children should be allowed near loaded firearms.
I don’t think children should be given loaded firearms, but I think that there’s a big difference between allowing them to mess around with guns, and having guns fired in their presence.
Fetishizing guns as such powerful and corrupting objects that children can’t possibly be allowed to even see them is just not a good way to deal with the issue. They’re tools, albeit tools used for a particularly unpleasant purpose, and there’s nothing wrong with showing them being used in a responsible manner, and I think the experiments described fit that.
It’s sort of the same situation as with alcohol– the pathological drinking culture at most American colleges stems in part from our stupid approach to the prohibitionist approach we take toward the drinking age. Alcohol becomes a fetish object, and kids become much more likely to abuse it.
Learning to properly fire a rifle ((and to cleans it, reassemble it, etc.) was an obligatory part of high school education back when I was in school. It was done at a military firing range, using military rifles, taught (in a very disciplined and safety-cinscious manner) by the military officers. This was a part of the defense strategy of the country at a time – in case of attack, every citizen is a soldier, gets a rifle issued and goes to fight to defend the country. I have never heard of anyone ever getting hurt during those exercises, but we have all learned a healthy respect for the weapons. I did middlingly with the torso-shaped target, but was one of the best in my school with a round target.
As for alcohol, I was given bevanda with my Sunday lunch at home since I was 5 or so. As teenagers, me and my friends experimented with drinking a little bit more, but there was always someone not drinking (a designated driver – though the term was not invented at that time yet). By the time we were 18, the allure of alcohol wore off and I don’t know of any of my childhood friends who drinks regularly – I don’t: I may have a bottle of a really good beer, or a glass of really good wine once every month or so, plus a champaigne at midnight on New Years Eve. Once I came to the USA, I went with some friends to a club (21+) and was floored – here there were adults in their twenties and thirties, excited about drinking, and behaving the way we did when we were 14.
The same goes for other “sins” – if you peruse Playboy when you are 12, you don’t care about porn any more by the time you are 17. Hard drugs were hard to find, so I never tried any. By the time I arrived in the USA and found it easy – there was at least pot everywhere around me – I was too old to get started so I never ever tried any of it.
On the other hand, not having a ban of cigarettes made it easy for me to start smoking at the age of 14 and I am still having problems, trying to quit every now and then, with transient or no success. Now we hear that smoking just one when young makes it easier to get addicted later on in life. Damned tobacco!
I don’t think children should be given loaded firearms, but I think that there’s a big difference between allowing them to mess around with guns, and having guns fired in their presence.
There is one teacher and 20-30 children in the class. What if he just turns away from the gun for a moment and some child gets its fingers on it?
My idea is that since it is possible to make such demonstrations without firing a gun (he could use a slingshot, for example), it’s better to do without it.
Learning to properly fire a rifle ((and to cleans it, reassemble it, etc.) was an obligatory part of high school education back when I was in school. It was done at a military firing range, using military rifles, taught (in a very disciplined and safety-cinscious manner) by the military officers. This was a part of the defense strategy of the country at a time – in case of attack, every citizen is a soldier, gets a rifle issued and goes to fight to defend the country.
You’re from Switzerland, aren’t you? I have no problem with military training for high-school students. After all, it’s impossible to do it without using guns. However, I think that it’s easier to ensure safety when the instructors are military officers and the whole lesson is about guns, not about someting else.
PS. My mother is a high-school teacher. She also thinks that firing a gun during a physics lesson is a crazy idea.
There is one teacher and 20-30 children in the class. What if he just turns away from the gun for a moment and some child gets its fingers on it?
That would be a problem, yes, but it’s just about trivial to avoid.
I can’t speak to the actual demonstration described in the article, but when I did this lab as an undergraduate, the rifle was held in a wooden frame secured with a padlock (the lab instructor had the key), and the frame was securely clamped to a lab bench. The gun was unloaded except immediately before being fired, and the lab instructor held the bullets. When we were ready to go, he would come over, load the gun, and watch as we fired it.
The chances of a student doing anything untoward with that gun were essentially zero.
The article doesn’t describe the demonstration in detail, but from what they do say, I very much doubt it involved leaving a loaded rifle lying around on a desk while the teacher’s back was turned.
My idea is that since it is possible to make such demonstrations without firing a gun (he could use a slingshot, for example), it’s better to do without it.
It’s nowhere near as effective a demonstration with a slower projectile. I’ve done it both ways, as a student and as an instructor, and the spring gun version just doesn’t make a tenth of the impression that the .22 rifle version did.
It’s nowhere near as effective a demonstration with a slower projectile. I’ve done it both ways, as a student and as an instructor, and the spring gun version just doesn’t make a tenth of the impression that the .22 rifle version did.
I can imagine that exploding 10 kg of TNT in the classroom would make an even bigger impression.
Slingshots don’t deliver their payload with the same speed every time whereas muzzle velocities are known for each gun. Therefore, there would be no way to verify that you actually got the right answer. As a former HS physics teacher, I believe that one of the most important things that needs to taught is that (1) physics (and science in general) works and (2) science is an observational exercise. I used the same (I suspect) smaller version that another poster mentioned above but would’ve loved to do something like that I did get us on an Army base and did the same thing with several pieces of artillery, though, and it was THE BEST lesson ever (yes they did calculations along with the artillery officer) so I can only imagine that the impact of a lesson like this would be impressive. If your mother is not a science teacher then maybe she doesn’t have the same perspective in this matter.
Listen – the US education system is doing a terrible job of getting young people interested in doing science. If this guy excites just one kid into studying physics in college, then I say “Go, Man, go!”
Imagine using this guy as the target. It’s clear he’s so dense the round wouldn’t penetrate at all.
so I can only imagine that the impact of a lesson like this would be impressive.
The point of the lesson is to impress children with science, not with guns. If the slingshot is not repetitive – so what? This means you can use the pendulum to calculate the average velocity of the slingshot bullet and introduce the concepts of mean and deviation.
PS. How about using a small crossbow instead of a slingshot? It would be repetitive.
PS2. Or make a device which uses a spring with known strength and test the Hooke’s law. Huh?
If your mother is not a science teacher then maybe she doesn’t have the same perspective in this matter.
No, she’s not. She teaches English. She doesn’t do it by cursing in English at children to “impress them”.
If this guy excites just one kid into studying physics in college, then I say “Go, Man, go!”
There are safer ways.
A spring device would be even better because you could change the exit velocity of the projectile.
This really isn’t going to go anywhere useful, so I’ll stop after this comment, but there are two points that make a real gun superior to a safer spring-loaded projectile launcher:
1) A real gun is less artificial, and makes the physics seem more relevant. A typical student is likely to be sort of curiour about how fast a real bullet moves, while not particularly caring how fast a projectile shot from some toy physics apparatus moves.
2) There isn’t another way to measure the speed of a real bullet. With a spring-loaded launcher, you can determine the speed a half-dozen other ways (fire it up in the air, and measure the height it reaches, fire it across the room and measure the distance it travels, etc.), all of which students find easier than dealing with the math for the ballistic pendulum. You can’t do any of those tricks with a real bullet, which helps drive home the power of momentum and energy methods.
And again, it’s a firearm, not the One Ring. Used properly, with reasonable precautions, the danger to students is minimal, and outweighed by the educational benefits. There’s nothing inherently evil or corrupting about guns– in fact, this being the US, a good fraction of the students in the class have probably already had closer exposure to guns than would be provided by this experiment.
What they probably ought to do is the MythBusters thing– arrange to have a police officer come to the class to supervise the firing, and keep everybody calm.
Back when I was observing classes for my teaching degree program, I spent time in a physics class taught by a Fulbright exchange teacher from England (or Ireland, I forget now). The topic was the conservation of momentum and he was ecstatic about being able to shoot a Daisy air rifle pellet into a toy car. Back home, such “weapons” were not legal. The students, of course, were less than impressed, it seemed.
As for shielding children from guns, it’s not a good idea. Too many kids have an unrealistic concept of firearms they have gathered from innumerable movies, TV shows and video games. Showing them a real gun, its operation, the report and the recoil seems to me to be a valuable education lesson.
And no I am not a member of the NRA and I do not have any firearms at home. We did, however, live for a quite a while in a rural part of the state. My daughter carries a card testifying that she passed a gun safety course offered by the Fish and Wildlife office at the age of 13 or 14. The experience did not scar her emotionally or turn her into a mercenary, a killer, a game hunter, an NRA member or even a Republican.
But I do have a question. How did this guy bring in a firearm into a school? In our area, every school has a “no firearms” sign on the door.
I was a student of Mr. Lapp’s. The demonstration is great. Below is a letter I wrote to the Tamalpais Union High School District Superintendent. He also does a wonderful Physics in Music workshop as well.
Dear Superintendent Ferguson,
I was extremely disappointed in your decision to ban Mr. David Lapp from doing his ballistic pendulum demonstration as reported in the Marin IJ.
I am a third generation graduate of Tamalpais High School. Mr. Lapp was my physics teacher. Currently I am pursing my Ph.D. in Molecular Biophysics and Biochemistry at Yale. From my graduating class, there is one person at Stanford earning her Ph.D. in genetics, one at UCSD earning his MD/Ph.D. in bioinformatics, one earning her Ph.D. in geology and numerous others who have gone into careers in the medical field. When I talk to professors and fellow graduate students here at Yale about my classmates they are surprised at the numbers especially when I tell them Tam is a public high school and the class size was 181. One of the main reasons my class has this wonderful level of continued participation in the sciences is due to the the excellent teaching we received in high school from the likes of Mr. Lapp and Ms. Brumbaugh that taught us science is not the facts found in a textbook but rather a method of studying the world around us to understand how the universe actually works.
That lesson is just as valuable for those that pursue interests outside of the sciences. They need to be able to evaluate risks and rewards. They need to fully understand just how ludicrous it is for those action heroes found in movies and video games to evade bullets like they do, to understand what a gun can actually do. To have any fears they have regarding guns based on reality and not media hype. They need to be able to apply textbook knowledge into the real world to evaluate whether fears are real or imagined. To do this, science teachers have to be able to engage students by doing demonstrations and having the students do experiments. I have seen and done the ballastic pendulum experiment at other schools, the demonstrations were not as effective in teaching the principles nor in engaging the students.
The greatness of the science teachers at Tam is that they are able to engage not just those interested and planning careers in the sciences but also those who are not while not sacrificing the knowledge, skills and lessons to be learned. That is rare.
My question to you, is why ban the demonstration? What is the relative risk as compared to other experiments/demonstrations done in science classrooms/labs? Are you banning it because of irrational fears or because the risk is far greater? Your quote in the IJ, “‘He does a lot of things to grab students’ attention. However, this garnered more attention from the public'” argues you gave into the former which is a shame. You are giving into the very irrational fear that science combats by denying a science teacher the means by which to combat irrational fears. The motto of the district is “preparing today’s students for tomorrow’s world”. Your students will be making decisions in the future with regards to global warming, stem cell research, genetic manipulations, flu pandemics to name a few. They need to be able to separate the fact and rational thought from false claims and fears. When a school administrator takes the easy route and gives into the irrational what lesson is taught to students? When those in leadership positions fail to lead? Fail to make a stand?
Where does it end? Do you ban the chemicals used in chemistry courses because they could be used to poison or to make explosives? Do you ban phenol/chloroform from being used in nucleic acid extractions? Where are you drawing the line? What is your rubric?
One of the major bedrocks of democracy is scientific thought. The critical reasoning allows for a society based on rational thought and not the irrational. If we continue to erode science and give into such fears, we will continue to move this society further from its democratic ideal.