Now, for use with your mousetrap cars – a simple way to test your mousetrap’s starting energy and spring constant! The Torsion Wheel energy tester has been designed for accuracy and simplicity. A string attached at the bottom of a disk and fitted into a groove along the top is pulled downward with a force probe or a spring scale. The student records the pulling force for every five-degree increment marked on the disk. The Torsion Wheel is made of durable, high-quality plastic. Lab activities are included.