Teaching physics of PWD to WEBELO 2's

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gotquestion
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Teaching physics of PWD to WEBELO 2's

Post by gotquestion » Tue Mar 28, 2006 7:43 am

Our second year WEBELO's will graduate before the PWD next Spring. I have spoke with the den leader and proposed we have a 1 to 2 day training session on the physics of PWD where we would discuss free-body diagrams, friction, CG, etc., build and race weighted pine wood blocks (no aerodynamics or asthetics considered).

Has anyone else done something similar? I'd love someone to share their experience and course materials. I'd hate to re-invent the wheel.

Also, do you guys have any involvement from your Boy Scouts? It seems a shame that they don't participate when they are finally old enough to actually build 100% themselves. It seems to me that they could learn a lot.


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Re: Teaching physics of PWD to WEBELO 2's

Post by gotquestion » Mon Apr 10, 2006 11:07 am

OK, It looks like no-one else has done this.

Do you think it would be too advanced for W2's to understand?


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Re: Teaching physics of PWD to WEBELO 2's

Post by Mr. Slick » Mon Apr 10, 2006 11:29 am

When I did this "physics" for the boys, I kept it real world for them.

The CG/COM issue is complex at the physics level and so to a 5th grader I tried to keep the examples real and result orientated(theoretical physics is not as fun as applied physics). Which ball is moving faster when it hits the ground, one dropped from 1 foot or one dropped from 6 feet?

What is the effect of moving the COM far away from the axle(pivot point)? This we did at a park with a teeter totter. . have an adult sit real close to the pivot and have the boys use the other end to move the adult up and down. Then have the adult go to the end of the board and have the boys try to move the adult up and down. This gives a real example of keeping the COM close to the pivot point and the energy used to move it when the axles hit a bump.

Wheel base and handling bumps is a fun one to explore -- especially if you have a short wheel base Jeep and a long wheel base limo for ride comparisons over some speed bumps. :-)

For friction I used a wood block tied to a string and had the boys pull it over a varity of surfaces. I used a sheet fo 60 grit sandpaper, 600 grit snadpaper and then a flat piece of wood. Try and get the boys to detect the starting effort versus the keeping it going effort. After evey one had done their pulls I "lubed" the board surface with some graphite and let them try again.

The final phase was to come up with a design that could be used to test the different variables. . . designing the ultimate pinewood derby test vehicle. This let them apply what they had experianced/learned and started some interesting discussions that revealed how they had been building cars. ;-)


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Re: Teaching physics of PWD to WEBELO 2's

Post by Nitro Dan » Tue Mar 13, 2007 9:49 am

I realize that this thread is almost a year old, but I agree with Mr. Slick in keeping it "real world" as much as possible. I took on the task this year of explaining the physics of PWD to my son's WOLF den. I've been contemplating how to do something like this with my own son, when last year (as a Tiger) I asked him if he knew why his car was so fast. His response was "because it was Yellow" and he was fully convinced of it. That's when I realized that he had gone through the motions of building the PWD car, had learned some of the tool skills, but did not understand the "why" behind each step that he did to the car.

This year I took a different approach (and started a lot earlier) and kept working with him on the "why" of each step until the "light bulb" turned on. I found mainly that visual experiments that show "why" are the most effective means of getting your point across.

Some of the points that worked out really well were using finger spin tests (having the boy do the counting) on the wheels at each point during the axle preparation (spin wheel on untouched axle, spin wheel after removing burrs, spin wheel after straightening/tapering the nail/nail head, spin wheel after polishing axle, and spin wheel after graphiting axle). This is a real eye opener for understanding friction with saying the word "friction".

For COM and weighting I took his out Hot Wheels track (duel racing lanes) and two small rubber balls. I explained that I was going to give one ball a head start and placed it six inches further down the hill. Then I asked them which ball was going to win. Immediately they pick the one I gave a head start to. When they see the other ball pass the one I gave a head start to in the straight-away, they (and the parents) are completely amazed. I ask them why their ball lost, and I get some extremely creative answers. After a few minutes they'll come up with the right answer. After that I take one of their cut cars and balance it on the edge of a file, then place a rubber ball directly over the balance point, to show them that the ball represent the cars COM. Then I go on to show them how we can move the "ball" towards the back of the car by adding weights to the rear of the car. This is when the "light bulbs" start to turn on. I also go on to show them what happens if too much weight in behind the rear axle, and where the ideal point of the COM should be.


-Nitro Dan


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Re: Teaching physics of PWD to WEBELO 2's

Post by Pinewood Daddy » Tue Mar 13, 2007 10:16 am

Nitro Dan wrote:I realize that this thread is almost a year old, but I agree with Mr. Slick in keeping it "real world" as much as possible. I took on the task this year of explaining the physics of PWD to my son's WOLF den. I've been contemplating how to do something like this with my own son, when last year (as a Tiger) I asked him if he knew why his car was so fast. His response was "because it was Yellow" and he was fully convinced of it. That's when I realized that he had gone through the motions of building the PWD car, had learned some of the tool skills, but did not understand the "why" behind each step that he did to the car.

This year I took a different approach (and started a lot earlier) and kept working with him on the "why" of each step until the "light bulb" turned on. I found mainly that visual experiments that show "why" are the most effective means of getting your point across.

Some of the points that worked out really well were using finger spin tests (having the boy do the counting) on the wheels at each point during the axle preparation (spin wheel on untouched axle, spin wheel after removing burrs, spin wheel after straightening/tapering the nail/nail head, spin wheel after polishing axle, and spin wheel after graphiting axle). This is a real eye opener for understanding friction with saying the word "friction".

For COM and weighting I took his out Hot Wheels track (duel racing lanes) and two small rubber balls. I explained that I was going to give one ball a head start and placed it six inches further down the hill. Then I asked them which ball was going to win. Immediately they pick the one I gave a head start to. When they see the other ball pass the one I gave a head start to in the straight-away, they (and the parents) are completely amazed. I ask them why their ball lost, and I get some extremely creative answers. After a few minutes they'll come up with the right answer. After that I take one of their cut cars and balance it on the edge of a file, then place a rubber ball directly over the balance point, to show them that the ball represent the cars COM. Then I go on to show them how we can move the "ball" towards the back of the car by adding weights to the rear of the car. This is when the "light bulbs" start to turn on. I also go on to show them what happens if too much weight in behind the rear axle, and where the ideal point of the COM should be.


-Nitro Dan
I heard some light bulbs clicking on now!! :idea: :idea: :idea:

I've told my boys about much of what makes a fast PWD car, but I don't think any of it has sunk in. The 2 balls on the Hot Wheels track is a great demo!!!

The past 2 years I've hosted Workshops in my garage for all who were interested in the Pack. Typically the fathers work on the cars while the boys play with my boys. Nobody learns anything other than I've got alot of tools.



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Re: Teaching physics of PWD to WEBELO 2's

Post by quadad » Mon Apr 07, 2008 8:09 am

Pinewood Daddy wrote:The past 2 years I've hosted Workshops in my garage for all who were interested in the Pack. Typically the fathers work on the cars while the boys play with my boys. Nobody learns anything other than I've got alot of tools.
Very interesting !

After some recent strong 'blow back' from a few parents in our Pack about "too many large fingerprints" (to quote a well known author) on some of the cars, I considered suggesting a Construction Clinic. I was fearful of the committment however (likely being a key contributor and having three cubs plus a sibling of my own competing) and wasn't sure this was the best answer.

I came upon the idea of a "Construction Clinic" (probably not original) which is similar to what was discussed in this thread. It would be aimed at getting the kids to learn more about what they were doing with this cars and a 'gut feel' understanding of the physics involved. I would "steal" the idea above with the wheels/axles, rig up a car that had flexible weight position, another car with a removable wind jamming top, etc. and explain as simple as possible how these things can make the cars faster. It would be easy to get the kids to participate, they could be right close to the track action while the parents were in the back. It might be kind of a demonstration version of Stan's "Pinewood Derby Performance Design" charts.

What I like about this is it places the emphasis back on the "Father (parent)/Son time for getting the cars made. Arming the kids with more knowledge should increase their interest and desire to do the work themselves. We could always add in some additional construction education, but the reality is that this information is quite readily available.

What do people think about this ? Who has done it before ? Any more/better suggestions or tips on making it worthwhile ? I'm all ears and I have time and a test track to prepare for it between now and next January.



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Re: Teaching physics of PWD to WEBELO 2's

Post by Randy and Son » Mon Apr 07, 2008 11:19 am

quadad,

I feel like I'm in the same boat as you are. I'd like to offer both a clinic AND a workshop.

The advantage of a clinic is that you get to teach the "why" part of it and try to get kids and parents to think a little. But I would also like to have a workshop to provide the tools and make sure that everyone has fair access to the tools.

But too many just want to know the "how" part because its faster and easier than trying to understand the "why". Because of that, I'm afraid that people will skip the clinic and just go to the workshop. Of course it might be possible to use time at a Pack meeting to do the clinic. Sort of a captive audience that way.

It tempts me to announce only a clinic and then wait to announce the workshop at the clinic. That probably wouldn't be fair to everyone but its a thought.

Randy



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Re: Teaching physics of PWD to WEBELO 2's

Post by quadad » Mon Apr 07, 2008 12:11 pm

Randy and Son wrote:It tempts me to announce only a clinic and then wait to announce the workshop at the clinic. That probably wouldn't be fair to everyone but its a thought.
Thanks Randy, I appreciate your thought about wanting to do both. My concern though is that you can never be "fair to everyone", at least not in THEIR eyes. I commend all those who put on the construction clinics, and rig up work cells and equipment for the Pack to use. My suspicion though is that whatever extent you go to, someone will find reason to gripe. Maybe this means I am stopping too short. Time will tell.

My thinking is to start with the Demonstration Clinic. See how that goes. And then maybe add some Construction clinic aspects. One thought I had was to do some construction in "demonstration fashion", presumably with basic tools that the great majority of the scouts could get their hands on somehow. For example, someone demonstrates their way of cleaning and polishing axles. Then let a few scouts do one axle each. A small crowd (den ?) watches. Then you move on to the next station and do the same with a few wheels, letting other scouts do a sample wheel. No one designs or builds their car there. But they all get some sense of the build and again "wet" their taste for doing more. Hopefully with the parent or grandparent whatever.

This additional activity wouldn't have to take that long, maybe an hour or two. Those that wanted to leave after the first (Demonstration part) and believe they know how to build cars, could skip it. What do you and others think of this "refinement" ?



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Re: Teaching physics of PWD to WEBELO 2's

Post by Pinewood Daddy » Mon Apr 07, 2008 12:41 pm

I've hosted workshops in my garage for the last 3 years. I've been to a few technical seminars where they try to fit a 1 week course into 6 hours.

Whatever you do in a short period of time will result in a "seminar" type of experience where alot of information is thrown out, a little hands on, and the attendee goes away with a spinning head and a little knowledge (which can be dangerous!). The only true way to do something is to take the time to do all the steps, preferably more than one time, to let it all sink in.

They might get a fire started in them and do some research to find out more, or they'll go away thinking you're hiding something. You can't please everyone.

I think, in the eyes of most parents, the PWD is just another Cub Scout activity (say it ain't so!!) and don't take it seriously. There will only be a select few that will see the light and get interested enough to find this forum. Even less will get as obsessed as us.



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Re: Teaching physics of PWD to WEBELO 2's

Post by quadad » Mon Apr 07, 2008 2:56 pm

Pinewood Daddy, do you think that if we aren't planning on much real hands on, we are better off just doing the Demonstration Clinic ? That way we could at least focus on some of the basic principles and get those better understood.



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Re: Teaching physics of PWD to WEBELO 2's

Post by dna1990 » Mon Apr 07, 2008 4:13 pm

I too struggle with how to host effective clinics or workshops. With a small group of just a few scouts and parents - you will get widely varying ideas and interest levels. You can try having two workshops, one aimed at folks who at best own a screwdriver. And another for the folks who have some experience or ideas, but just lack the setup space and bigger tools like drill presses and jig/band saws, etc.

But the problem now is time. To do it right (in my mind) you need several workshops over periods of weeks to set in the basic foundations (of even just shop safety and tools, let alone PWD). Then allow that info to be 'slept on' and come back with more questions and ideas the next time.

Few, very few, in my pack have that amount of time to invest.


Changing the subject over to the clinic side, I tried a simple KNex creation. A string was wound around a shaft of a wheel. The string is then placed over a pulley up top and the tied to a 'weight'. First trial, wind the axle up so the weight is half way up the structure. How 'fast' does the wheel spin when the weight is released? Now add some weight to the weight, try again. Now wind the axle up so the weight is the highest possible point of the pulley. How fast, and how long will the wheel spin now? Lastly, wind it up full again, but allow a piece of paper to ride/scrape on the wheel...But I don't think I set off any light bulbs...it was too abstract from an object going down a 'track'.


One of the thoughts about this too, is why PWD can be so popular. If you are interested in 'creative' things, build a whacky dinosaur car. Interested in woodworking, carve a duck decoy and varnish the natural wood. Interested in tools or machining, construct jigs or cut intricate shapes into your block. Like painting, ghost flames and clear coat. Like speed, grab the last milliseconds from an axle burr. Like stats or math, study speed trends and lane variations. Like hoopla, create crazy banners and decorations for the race itself. I could go on.

Scouts - creating relatively safe environments for kids to find or polish their interests.

My first year wide-eyed goal was to make each workshop participant knowledgable in shop safety, and basic wood shaping. I think next year, my goal will be to simply let people have access to my thoughts and shop, but just that 'exposure' is enough for them to take away. If a spark exists, they will come back or find outlets on their own to further refine their skills and interest.

I am not running a commerical venue where a specific product or service is the goal (a fully built, painted, and fast car). But rather the relatively safe environment for you to accomplish that on your own.



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Re: Teaching physics of PWD to WEBELO 2's

Post by Pinewood Daddy » Mon Apr 07, 2008 7:13 pm

quadad wrote:Pinewood Daddy, do you think that if we aren't planning on much real hands on, we are better off just doing the Demonstration Clinic ? That way we could at least focus on some of the basic principles and get those better understood.
I like the Demonstration Clinic! If you can get the basic physics points across and how the apply that could raise interest in the PWD.

My workshops are a 2 or 4 hour window that I individually show people (the parents) the steps from transferring the design to the block, to axle & wheel alteration. They learn by doing every step, sometimes the boys even do some. But mostly it's easier for the parents to use my tools to build the car faster and somewhat better than they could at home. I state at the beginning they will build a competitive car, but building a Pack winning car takes many more hours paying more attention to details.



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