Tag Archives: physics club

Inspiring Younger Students with Near-Space Balloons

On Sunday, my school’s Physics Club launched their third annual near-space balloon. It was a fantastic success this year. Our first year, we simply focused on launching and retrieving our payload with photos and videos. Last year, we focused on gathering data (temperature, pressure, radiation). This year, we focused on inspiring younger students in our school district.

High school students in Physics Club contacted former teachers at the elementary and middle schools and asked if they would be interested in collaborating on the design and construction of an experiment to be launched to the edge of space. Four schools accepted the challenge. The high school students visited the classroom to introduce the project and followed up with additional visits in person or via video conferencing.

The ideas generated by the younger scientists were amazing. One elementary classroom wanted to see what would happen to Jello and popcorn throughout the flight. Another explored the effect of pressure on Peeps and sealed rubber duckies containing water or air. One classroom painted craft sticks with nail polish that changes color based on temperature and UV radiation. Another put condiment packages in a payload and filmed them throughout the launch. The final experiment was testing how a battery powered light changes throughout the flight.

We launched from a new location this year to provide a greater buffer between the predicted landing zone and the no-fly zone around Chicago due to the NATO summit. We didn’t want a F-16 shooting down our experiments. We experienced a near-failure due to under filling the 3000-g balloon, but we recovered and had a successful launch. Due to a grant we received from our district’s educational foundation, we were able to purchase new equipment so we could track the balloon throughout the flight. We installed an APRS transmitter on the balloon that sends GPS coordinates over the HAM radio band. This signal is picked up by repeater stations throughout the area as well as by our own rig which we interfaced to a computer to map the location of the balloon. It was quite a different dynamic this year as we knew the location of the balloon every minute. We hung out in a McDonalds and tracked the balloon; the whole group cheered when we passed 100,000 feet. You can export the tracking data from aprs.fi and display it in Google Earth.

Flight path

The balloon reached a maximum altitude of 105,330 feet (~20 miles) and the flight lasted 2 hours and 34 minutes. Here is the video of the flight:

We also created an album that contains videos of the preparation for the launch and the analysis of each school’s experiment after the launch.

This year’s project would not have been possible without the support and efforts of many people. The Naperville Education Foundation, Space for All, Adler Planetarium, and W9BKO. In addition, several science teachers from my school contributed and alumni with much needed expertise assisted. Finally, the classroom teachers who accepted the challenge of this project late in the school year made it an amazing experience for all of us.

If you are interested in launching a near-space balloon and have questions, please don’t hesitate to contact me. My colleague and I have presented our tips for launching your own near-space ballon which you may also find helpful.

Ping Pong Ball Cannon

The ping pong ball cannon is one of the demos that we perform for our Halloween Demo Day. As always, the question arose of just how fast the ping pong ball is traveling. Students began asking what else the ping pong ball could shoot through. When I shared that we were firing our ping pong ball cannon on Twitter, I received this reply:

Tweet

This sounded like a challenge for Physics Club. I also wanted to film the ping pong ball with the high speed camera again in order to try and determine the velocity of the ping pong ball. While we were at it, we decided to have some fun:

The raw video footage was filmed at 1000 fps. The camera films the carnage indirectly via a mirror in order to be protected from the debris.

Here is the video used to determine the velocity of the ping pong ball. The ping pong ball is only visible for five frames and is pretty blurry, but it works. (Although our technology specialist commented that we really need a 10,000 fps camera; I’m keeping my fingers crossed!)

Here’s the graph of the ping pong ball’s horizontal position vs. time with the velocity calculated:

Ping pong ball graph

Based on the video analysis, the ping pong ball is traveling at 167.2 m/s or 374 mph.

I’ve used the ping pong ball cannon as a sample problem when studying the work-energy theorem:

Calculate the velocity of a 2.3 g ping pong ball as it leaves a 1.5” diameter air cannon that is 2 m long. Assume that we completely evacuate the air cannon and the force remains constant as the ball is expelled.

F = P A = (14.7 psi)(π)(.75 in)2(4.45 N/lb) = 116 N
W = F d = (116 N)(2 m) = 231 J
KE = 1/2 m v2 = 1/2 (.0023 kg) v2 = 231 J
v = 448 m/s = 1003 mph

So, in reality the ping pong ball is traveling much slower than the theoretical maximum value. I expect this is due to the limitations of our vacuum pump. While the ping pong ball does experience air resistance once it leaves the pipe, I was surprised how far it appeared to travel before slowing noticeably (which is reinforced by the video analysis).

Oh, and when we fired the ping pong ball into three empty soda cans, it passed through the first two cans and embedded a fragment of itself through the wall of the third!

Physics Club and the Row-Bot Challenge

Three years ago my instructional coordinator encouraged myself and another physics teacher to start an after school club for students to “do cool physics stuff.” That first year, we focused on building small projects related to physics. We built candle-powered steam engines, homopolar motors, LED throwies, vibrobots, and styrofoam plate speakers. Two years ago, we started with the small projects, but then the students were inspired to launch a near-space balloon. Once the students set their minds to lauching their own near-space balloon, the club transitioned from a primarily teacher-led organization to a student-led one.

Last year, we started with a ping pong ball launcher challenge. After this kickoff, students decided to build a large hovercraft in the fall and then take it on tour to share with the community and excite people, especially younger students, about STEM. In the spring, we launched our second near-space balloon.

While Physics Club has increased in popularity and size in the past three years, we were amazed when over fifty students stayed after school on Friday to join Physics Club. We’re still figuring out how to keep this many students engaged and what our big project will be for the fall. To keep everyone active while we figure this out, we introduced the 2011 Physics Club Row-Bot Challenge:

The club will document this project on its web site. I’ll let you know how it goes.

Why the Row-bot Challenge? Well, we are considering building some sort of remote-controlled craft that can film video hundreds of feet underwater. This challenge may be a good precursor for that.

In addition to kicking off the challenge, the students had a great time filming with the high-speed camera. They are still trimming the footage and preparing the website, but here’s one of my favorites:

We also borrowed a thermal imaging camera that is normally used to diagnose computer hardware issues. While we don’t let the students use this camera, we still found some interesting things to image. One of my favorite was this comparison of an incandescent, CFL, and LED light bulb:

thermal images of light bulbs

While not planned, we also debunked those ghost TV shows. One student noticed that the camera was picking up what appeared to be a thermal ghost inside the adjacent room. This was puzzling until another student realized that the “ghost” was simply my infrared reflection off the glass door in the adjacent room. Science for the win!