How to Build a Rat Trap Car

Do you know what a rat trap car is?
If you don't know yet, let me take you to wikipedia:
http://en.wikipedia.org/wiki/Mousetrap_car
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A mousetrap car is a small vehicle having only one form of motive power being from a mousetrap. Variations include the use of multiple traps, or very big rat traps, for added power.
"

Get the picture? :)
Its quite easy and fun to build this rat trap car, they not only to kill rat, but also for race lol...

If you interested in making the rat trap car then here the guide from ehow:
http://www.ehow.com/how_5852910_build-rat-trap-car.html
A rat trap car uses the kinetic power in the spring of a rat trap to propel the car. One end of a string is attached to the trap arm and the other is attached to an axle of the car. When the trap is sprung, instead of snapping shut, it pulls the string slowly, turning the wheels and making the car move. The car can be constructed from wheels and axles salvaged from toys or bought at a craft store. The rat trap and other parts can be purchased at home improvement stores. The car can be constructed several ways. This design is one of the easiest to build.

Things You'll Need
- Large wooden, spring-style rat trap
- String, 10 inches long
- 4 small eye screws
- 2 sets of wheels with axles

Masking tape
Difficulty: Easy
Instructions:

1. Screw two eye screws into one end of the rat trap 1/2 inch from the sides. The screws should be aligned so the openings will hold the axles for the car. Repeat the procedure on the other end.

2. Place masking tape in the center of one of the axles of the car. Insert this axle through the eye screws on the end of the trap where the spring arm will be when the trap is open. Put on the wheels. Insert the other axle and put on its wheels. Ensure that the wheels do not bind against the body of the rat trap.

3. Tie a loop in one end of the length of string. Flip the loop around the masking tape on the back axle and slip the rest of the string through the loop. Pull the string to tighten the loop around the tape on the axle. This will prevent the string from slipping.

4. Set the trap. Wind the string onto the rear axle until all the slack is taken up. To start the car, simply spring the trap with a long stick. As the arm closes, it will pull the string, causing the string to unwind, turning the axle, and propelling the car.

Tips & Warnings
Rat traps are very strong and can injure you, if care is not taken. Never trigger the trap with your finger.