However, once set into motion the device can use the gravitational potential energy inherent in the starting elevation. Total mass of the device may not exceed 0.5 kg. The traveling part of the device must include the entire ruler. The device must start in contact with the top desk surface. The device must operate independently without operator input subsequent to being set into motion.
Construction materials are limited to the list attached.
The device must be capable of repeated performances. The device must not damage or permanently alter the desktops in any way. Contact must be made with a desktop to score points. Only the first contact with a desktop scores points. When any part of the device touches the floor or a seat the test will be considered ended.