Rat trap car built for torque

Recently for a school project my physics class has to build rat trap or mousetrap cars. the cars would participate in a speed race that would sometimes result in a tug of war. during the race i saw many spectacular and original designs. some with gear boxes, others with brakes to stop themselves from being pulled back and some just simple. In the end the simplest design seemed to win however it was quite the competition. Uploaded to youtube i have a video talking about my rat trap car and also recorded bits from competition day.

http://www.youtube.com/watch?v=UNQ9aRkPrHc

I found that this was a very exciting and competitive project and recommend if you have any spare time on your hands or are looking to try something cool out, to try this with some friends or family. The competition that i find would be the best to do is to have the cars start at a line and everyone releases at the same time, seeing who's can travel 1 or 2 meters he fastest. You could also simply build them for distance and wee which travels faster or you cold do a tug of war/ race like we did in class where the backs of the cars are tied together and both race to get off the edge first. however mousetraps are much easier to work with and easily obtainable.
 If you are looking to try a race out like this here are a few tips:

More speed / acceleration - smaller wheels
More distance - larger wheels
More torque - larger axle
More distance - smaller axle
More distance - longer pulling arm
More acceleration - shorter pulling arm
-to get more traction put elastic bands or rubber around the wheels
-also to increase traction you can make the car heavier however weight reduces acceleration

Homemade crossbow made of household materials

Need something that will appeal to your or your child's creative side, get them off the computer or something interesting to do when your bored? Try building this crossbow, its built all out of household materials, it is easy to make and simple to do yourself. From a kids point of view it fun to play with, and feels good to build something that you can use and works. from a parent's view it teaches your child creativity, mechanics, elastic and potential energy and gives them the hands on experience that school doesn't teach

Materials:

-2 sheets of paper

-2 thin flexible Popsicle sticks

-Glue and tape

-an elastic band\

-a straw (bullet)

Start off by rolling 2 sheets of paper. one width wise. the other width wise but folded in half width wise as well. tape the rolls after they have been rolled cut the wrinkled edge off the short roll. The one with the crease.

tape and or glue the two rolls together

glue the popsicle sticks to top roll . far enough apart that a straw can it through

attach the elastic band to all 4 ends of the popsicle sticks

put glue in the end of a straw to give it wight.