how to  make a car with a box and runs off balloons?
537936
Use a shoe box.  Tape on some wheels and axles.  Put the balloons inside the box with the base of the balloons taped so all the air will go out the back.  When the air is released it will form a primitive rocket, propelling the box-car across the floor.\n\nI can't say this isn't rocket science, because technically, it is.
719052
Very very simple. Take a baloon ( white or any light color), blow it to its complete size. Then, tie it at the end so that the air does not go out of the baloon. Then paint on it as the planet should be. Par example, Paint with blue and brown for the planet Earth. If you want to hang it, use a wire.
514165
This is what you will need,\n\n1 Cork board cut into a 6x4 inch rectangle\n1 moustrap\n4 old Cd's for front and rear wheels\n1 1 inch dia. dowel rod cut into a 2 inch long piece\n2 coat hangers to cut for axels\nDIRECTIONS:\n Cut a section out of the cork board at one end wide enough that the 2" dowel rod will fit. use piece of hanger as axel trough dowel, place a small nail as post for rubberband in dowel, attach cds to each side of hangers, glue mouse trap to top of cork board tie rubberband to spring arm, and then wrap it around the dowel until it is tight. as the spring arm goes down it will turn the shaft which will propel the car forward.
149177
The other posters have all given good answers.  Think about scenes you see set up in a museum - they are large scale dioramas - your sister's will be a small scale version.  \n\nYou might want to paint the inside of the shoe box or line it with a fabric that will be a good one for the project title.  My kids used pictures cut out of magazines glued on popsicle sticks if they needed to stand up, plasticene, bits of stick, grass, stones, leaves, miniature figures and furniture, etc. (depending on the topic) from the dollar stores, play dough shapes, aluminum foil to represent rivers sometimes, artificial snow spray, anything that would add to the appearance. \n\nPlanning is important - you might want to have two shoe boxes in case you need to start over.  But overall it is an easy and fun project, and painting the inside of the box with a simple scene goes a long way toward creating a good diorama.\n\nI hope this helps.
6436
Practice, prefereably with non brakable objects to represent other cars - cardboard boxes and traffic cones.\nI found it helped to visualise the car from outside but some people think i'm crazy.
43265
do a thing with conservation of momentum. make your own newton's cradle(or use one if you already have one). you'll need 5 balls of exact equal mass(marbles would work) glue string to each one and tie the other end to a rod or stick of some sort(make sure the strings are the same length, and the balls have to be perfectly lined up and touching). find a way to get the ends of the rod to rest on something to make the balls/marbles hang down. ok, now pull one back and let it slam into the line of them. they will all stay still except for the last ball on the other end, which will fly up, come back down, and hit the row of them again. if you take two balls and pull them back, two will come off the other end. same with three, even though there are only 5 balls. the middle ball will go twice, and the ones that come back down will always stop dead once they reach their original position and the others start moving.  this is because they transfer their momentum to the other balls. the reason that the same number of balls come out the other end is that the masses have to be equal before the collision and after.  the system will not go on indefinately as it will eventually be slowed and eventually stopped by friction and air resistance.
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.
240987
put the opening of the balloon on the spigot of the helium tank.  they are usually made of rubber.  when you tip the spigot to one side, helium comes out.
1092821
you could porb try an internet site like howstufworks.com
438403
You can use air compression if you can't find fireworks.  Rig something to blow its top and throw some top cover into the air.  Sound effects will add to it.  The container could contain smoke that you've trapped in it to release.
797698
use old cardboard boxes and some spray paint
180954
A car that does not use gasoline or diesel
181915
set up variables for everything.\n\nFor example: 7200 cars.  3200 four seaters.  then the rest is 7200-3200=4000 six seaters.  the 4 seaters are 100% full so 40000 people.  the total is 80% full thats 80%*(4000*6 + 3200*4) etc
1052452
make anything out of the following\nperiscope\nvolcano (Although I don't suggest this - it is a very old project and maybe many will turn up using this)\nA mini hovercraft or hot air baloon (info can be found on net)\nI don't know what it is called but if you know that thing in which we have to take a small hoop across a wire (which is not straight) without touching it. If touched, it will make a sound.\n\nIf none of this suits you, you might watch Backyard Science at National Geographic Channel
428194
Limbo, Pinata. Musical Chairs, Pin the Tail On the Donkey, Dance contest, Pop The most Balloons, Simon Says, Toss the egg or water balloon, spoon race, 3 legged race, sack race, eating contest. You can do Arts And Crafts.... Have the kids fill sand bottles, paint bird houses or other inexpensive wooden items. If you go to your local ART & CRAFTS Store you can get many of the items at very little costs. You may also see some other ideas there. Good Luck!!!
805939
Alternatively, you might way to try filling a 17" x 17" x 7" box with tiny chopped up styrofoam.  You might have to experiment with the size to make sure that the egg doesn't push all the way to the bottom and crack.  The idea is to maximize the size of the crater the egg will make without bottoming out, which means maximum distribution of transferred kinetic energy. Maybe you can have larger pieces at the bottom, and use sucessively smaller pieces towards the top of the box, to avoid having to experiment much with the sizes.
500012
make a catapult or a trebuchet\nmake a lever\nmake a hydraulic lift ( soda bottle hosing balloon housing for balloon like a box or can, something to lift}