Posts Tagged ‘rockets’
I started building model rockets with my students this year and I’m glad I did. Most of my students have never built or launched rockets before. A few did in eighth grade, I think maybe two or three did with their parents, but out of the 100 or so seniors that I teach, that’s was it. About 80% of my students are college bound and only a couple of them are going into science or engineering, so connecting a subject like physics to something hands-on is critical to their understanding of the material. Not that I think most of them understand it, but let me delude myself please.
The school purchased one rocket for every two students. I know in some area schools, the students are required to purchase the materials. I know that most of mine could, but quite a few can’t. So the school paid for them. It took about three days to build and paint the rockets. They build, I paint. I knew I had to when one of my more trusted students came in with a rocket dripping paint. “Several light coats are better than one heavy coat.” Didn’t matter how many times I said that, apparently it didn’t stick.
The next nice day we all trudged out to the field, took lots of pictures posing with our rockets, then we launched them one at a time. I tried to explain how high and how fast they go, but until they saw it they just didn’t get it. A few dramatic failures are good. We had one tail fin fall off because it wasn’t glued on well. The rocket looped just barely over our heads. A few had the nose cone too tight. The ejector charge couldn’t pop off the nose cone, they come down fast and tend to stick in the mud. We even had one actually explode. I’ve never had that happen, I think it was an engine failure and not the work of the student. All these events add to the teachability of the lesson. We learn from our failures.
As a follow up homework assignment, they each had to write an article telling about the project, the launch, and explaining the theory to someone who hasn’t had physics. I chose two of the articles and a couple of photos and submitted it all to the school newspaper for publication.
- Each group got a single A engine with the rocket. If they wanted to launch again, they had to purchase an engine for $2. I had some B and C engines, but our field isn’t very big and we lost anything launched with C’s.
- I wanted the kids to purchase the rockets for $2, but only a few did. I would either get them to purchase them up front with their own money or just give it to them. The teams would have to decide ahead of time which of the two gets to keep the rocket.
- I bought a mix of Viking and Wizard rockets. Both are good, they use streamers for recovery rather than parachutes. A parachute in a 10 mph wind will drift twice as far as it is high. So if it goes up 500ft, it will drift 1000ft.
- Walmart is the cheapest place to find engines. A three-pack is under $5.
When I teach projectile motion, I like to do exercises where the students have to predict the results and then perform the experiment. One of my favorite toys is something called Stomp Rockets. They aren’t as easy to find as they were 10 years ago. They are plastic rockets that are launched from a tube and plastic bladder that you stomp on. If you set the angle to around 45° and jump up and come down hard with your heals, you can launch a rocket the length of a football field. If you launch them straight up, you can use a stopwatch to determine the maximum altitude. This is obviously an outside activity, but there are also foam rockets that we have launched in the gym. Outside is more fun.
I built a supersized cardboard protractor to set the launch angle and I had to rebuild the launch stand because it just wasn’t sturdy enough. The challenge is that you can’t get the same launch pressure twice, so the lesson has to be generic enough to get the point across without getting accurate results. We tend to experiment with the relationship between the launch angle and the distance.
I’ll put some pictures here some day, I haven’t done the activity in quite a while.
This is a favorite of the students. After studying Newton’s Laws of motion, we spend a day making rockets from paper match sticks. The process is simple, tear out a paper match, cover the top with a small piece of tightly wrapped aluminum foil, heat the match with a lighter and watch it launch.
Students will typically make at least three of these in a class period. Most go no more than an inch or two, many doing that backwards. Last year one match went 26 feet. This year, I believe the record was 18 feet. Credit goes to Richard White for sending me this last year.
The directions call for making the exhaust tube with a paperclip. That hasn’t worked well for us, the hole is too big. I’ve seen other directions that use a pin. I haven’t tried it with a pin, but I’d like to. In class, we simply wrap the tip tight and count on the gases finding their own exit.
Note: This is an outside activity unless you have a really well ventilated lab, which I don’t. Also, spend $5 on a BernzOmatic lighter. You can get it from Walmart. Aim for a day with very little wind otherwise you will have a hard time keeping the rockets on their launcher and even harder time getting them lit.