About Mousetrap Cars
Those little wooden mousetraps that snap and kill mice who try to get the cheese or peanut butter can be used to power toy cars. Teachers use mousetrap cars as assignments to teach their students about physics and the process of engineering and inventing. Then the students race the cars they built competing for prizes for the fastest or the farthest. Here's how you can build your very own mousetrap car.
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Identification
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Mousetrap cars are built from Victor mousetraps (see Resources below). Four wheels are attached to the wooden platform of the mousetrap, which is 1 3/4 inches wide and 4 inches long. If you wind a string on the axle of one of the wheels and attach the same string to the snapper arm of the mousetrap, as the car moves forward, the string will unwind quickly as the action propels the car forward. The trick is to wind the string in the opposite direction from the way you want the car to move. Another way to power a mousetrap car is to use rubber bands attached to little eye hooks drilled into the wood.
Features
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Mousetrap cars can travel distances from around 25 to 45 m at a speed of up to 5 m per 1.2 seconds. The length of your string or your rubber bands will determine how long the mousetrap car will be able to go. The size of the wheels also effect the distance that the car can travel. Large wheels with small axles go farthest.
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Types
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It takes creativity and research to figure out what kind of wheels will work the best on your mousetrap car. Experts recommend using CDs or DVDs for wheels (see Resources below). Other people make cardboard, wooden or metal wheels. Whatever you make your wheels from, if you want your car to go fast, you have to reduce as much friction as possible. This can be done by applying graphite powder to the wheels.
Potential
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MESA, an organization devoted to mathematics, engineering and science achievement, holds annual mousetrap car competitions for 2-person teams of students from sixth to twelfth grades. The mousetraps are not allowed either to be disassembled or changed other than to attach it to the wheels. Then the cars race twice in an order that is determined by the judges. The winning team built the car that went the farthest overall and the prizes are ribbons. The teams are also judged based on the engineering ingenuity demonstrated in their car's design.
Expert Insight
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The University of New South Wales in Australia holds mousetrap car competitions for the mechanical engineering students. Obviously the caliber of these high-tech mousetrap cars will be better than the ones for high school or middle school physics projects. One of the most valuable things that you can learn by working on a mousetrap car project is that when you design something that has to work and involves engineering, there is a lot of testing and experimenting, trial and error, and starting over. It takes real patience to make a mousetrap car that really works.
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