General theory of practical method: door hinge and the vertical axis. Lever and the pivoting point. Presenter: Chen Zhonghua Length: 17 min. In: English Year: 2013 Difficulty:1/5 At: Oakland, CA. USA
lever
Three aspects are important.
- The stick/staff must be strong. If it bends, it can not bend in a way that energy stops.
- There must be a pivoting point. The pivoting point must not move.
- The level should be longer than the load.