# how to make a mousetrap car

December 08, 2013

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#### Mousetrap cars and energy

By Doc Fizzix // Published Nov 17, 2005

Perhaps the concept most central to building mouse-trap powered cars is the concept of energy. Energy is defined as having the ability to do work. Work is motion that result in something being done. Without energy, the universe would be motionless and without life. We usually observe energy only when it is happening or when it is being trans-formed. Energy can be classified in a number of ways. Most commonly energy is classified as potential and kinetic. The energy that is stored and held in readiness is called potential energy (PE) because in the stored state it has the potential to do work. For example, a stretched or compressed spring has the potential for doing work. When a bow is drawn, energy is stored in the bow. A stretched rubber band has potential energy because of its position and because in this position it is capable of doing work. Kinetic energy (KE) is energy of motion or the energy a moving object has. A baseball thrown through the air has kinetic energy because of its motion just as a moving car has energy because of its speed or motion.

Energy, potential or kinetic, follows one basic rule called the Law of Conservation of Energy, stated: Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes. By winding the spring on your mouse-trap car, you store energy in the spring as potential energy. This stored potential energy will turn into kinetic energy as the mouse-trap car begins to move. In a perfect universe, your mouse-trap car should roll forever as the potential energy is changed into kinetic energy. But in our universe there is friction and in order to overcome friction you have to do work. Friction converts energy into heat and sound which removes energy from your motion, causing the vehicle to roll to a stop as its energy is removed. Your goal in building a good distance car is to produce a vehicle that loses energy at the lowest possible rate.

When designing a mouse-trap powered car, there are two variables that truly determine the overall performance of the vehicle and they are: friction and energy. Friction is the force that works against motion causing and object to slow and stop; energy is what moves and object or keeps it in motion. If your vehicle encounters too much friction, your energy supply will be consumed (used up) too quickly and your vehicle will not travel as far or as fast as you would hope. Evaluate every moving component on your vehicle and decrease the amount of friction at each point. As a general rule of thumb, the more moving components that a machine has, the greater the force of friction will be and the greater the energy consumption will be. Your ultimate goal when building a distance mouse-trap powered vehicle is to reduce friction to the lowest possible force. The smaller the frictional force, the farther your supply of energy will propel your vehicle. With this idea in mind, slow-moving vehicles will have a smaller force of air resistance acting against them and will travel farther than faster-moving vehicles. USE GRAPHITE POWDER on moving parts!

See the following related articles to get started:

basic mousetrap vehicle propulsions (how to make it move)
how to make a good distance traveler
how to make a good speed-trap racer

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