how to build a balloon powered cars?
114124
Probably the simpliest way I can think of is just to strap the balloon to a set of wheels and position it so that the opening is point in the opposite direction you want the car to move.  When the balloon is released, the air can escape out the hole and propell the car forward.
403852
We used to build a Go-Kart frame similar to the store bought and make enough room for the Engine to mount behind the Seat. IF, it not have electric start take into consideration room to use the kick starter or mount a Rope Pull maybe using a compression release. Make a rod to run where you want the hand shift and use pedals for Clutch, Brake and Gas. Good Luck, it a fun project and you should be able to use a nice size tire, look for a cost effective Tire set up.
545902
Really easy project: http://www.hilaroad.com/camp/projects/clinometer/clinometer.html\n\nEasy trebuchet: http://hila.webcentre.ca/projects/trebuchet/index.htm\n\nEasy dome: http://www.hilaroad.com/camp/projects/dome/dome.html\n\nMeasure the diameter of the sun with geometry: http://www.hilaroad.com/camp/projects/pinhole_sun/sun_diameter.html\n\n\n\nA suspension bridge would be a nice project because the shape of the main cables that holds up the bridge is a mathematical curve called a "catenary."\n\nhttp://www.infovisual.info/05/028_en.html\nhttp://en.wikipedia.org/wiki/Suspension_bridges\nhttp://en.wikipedia.org/wiki/Catenary  (This article explains that the St. Louis Arch is an inverted catenary, and it even gives it's dimensions and the formula of the curve.  You could make a scale model.)\n\nAnd, it looks like I'm wrong  about suspension bridges.  Their main cables are parabolas, because of the weight of the deck.\n\nHere are some more projects you can check out:\n\nhttp://www.astrocappella.com/activities/cosr_lp.html (make the umbrella rigid by painting plaster on it)\n\nSolar reflectors would be good projects using parabolas: \nhttp://www.hilaroad.com/camp/projects/solar_energy/Hila_Solar_Energy.html\nhttp://www.cockeyed.com/incredible/parabola/parabola.html\nhttp://www.humboldt.edu/~ccat/solarcooking/parabolic/parabolic_solar_cooker_pg_3_html.htm\nhttp://peacecorps.mtu.edu/solarcookers.htm\nhttp://jc-solarhomes.com/fair/parabola20.htm
941395
I had to do this before, but I had to make mine out of candy. If you're allowed to do that, use candy. It's pretty easy. Just get some wire, twist them to the right shape, and use different kinds of candy on them. Once you have those up, then you'll need the wires that go across to connect them. I find that candies like twizzles and gummy worms work well. It shouldn't take that long to make. Good luck!
956561
Build a Van de Graaf generator.  Read the following article in Wikipedia:
651250
It depends on where you live. Some flower shops also sell balloons and will inflate them,a balloon shop, sometimes a Hallmark store, some Wal-Marts have helium tanks. Just check the yellow pages of your local phone book. You should be able to find some place that will do this for you.
542150
Because the air and all objects inside of the car are going the same speed as the car, try driving around a corner with a helium ballon. If you take a right corner the ballon will go to the right side of the car while you go to the left side.
430220
tie a string to the tooth and on the other end of the string tie it to a car and have someone takeoff
223669
best site for help.\n\nhttp://www.scioly.org/obb/index.php\n\nLook for posts about the "scrambler car"\n\nThese will be advanced designs for competition, but you will get the general idea of how to build one.
134797
http://www.howstuffworks.com\nThey may have a link.\nThey did for building a wind powered generator.
131961
The gasoline-power requirement is going to be the challenging part.  I'm familiar with several ride-on scale model trains, but they're all electric power.\n\nStart with the link below.  It should be a good starting point for you.
520077
Have you tried the Pressurised Bottle Rocket?\n\nEasily constructed with used plastic bottles. What you need is a pump, cork and a tube. Build some tail fins to stablise the rocket for flight. You need to put in some water in the bottle. Then just pump the pressure up and you have an entertaining setup.\n\nHave a challenge who can shoot the highest and then parachute the Rocket down. The highest and/or the longest hang time wins.\n\nYou will need a field to do this properly though.
784055
The way to do this is to first work out the acceleration required to turn the car round the curve.\nFrom there it is a simple matter of working out what angle the road needs to be at so that gravity will provide that acceleration.
1172427
Hey if you really want to know go to: http://www.gemcar.com/  not only can you find your answer it will tell you how to build one......good luck
117346
Well i remember I did a research on hidroelectric plants. And the good thing is you can make aworking model using some water and a bicycle generator hooked to a small light bulb (holiday decoration ones or others like that) also any kind of research that involves things the evaluator can actually see working and moving is always a plus. Just stay away from volcanoes, while they ARE very interesting, its been done quite a few times. Hot air ballons are cool, some china paper glued to make the ballon and a aluminum plate with a candle to keep the air warm (you inflate it with a hair dryer) and you have yourself a working model, plus you have all the data refering how hot air is less dense than cold air etc...there are a lot of cool things you can do out ther and believe me Internet IS going to be VERY useful
972209
a balloon filled with petrol next to some wire wool....that should do it
22927
go to a store that sells KNEX (toys-r-us) they have a set that has a motor on it. you can make the whole thing out of it or just use the motor.