A simple snap-back mousetrap is a clever machine. With just a few parts (a wooden base, a spring, a metal bar, and a trigger mechanism) it can do its job quickly and efficiently. When a mousetrap is set, the spring in the center is compressed, becoming a source full of potential energy. This energy is being stored, not used, but as soon as the trap is released, it is converted to kinetic energy (the energy of motion) that propels the snapper arm forward. This is a perfect example of conservation of energy. It takes an amount of force to set the mousetrap and when the trap is triggered, it creates a force onto the mouse that triggered it.