Seesaw

It is a gravity toy. Reasonable dimensions of violet rack teeth and yellow bar rectangular hole make the seesaw motion possible. Center of mass of the bar including two pink weights must be lower than contact points between the bar and the rack Calculation of this mechanism is not easy because the inertia and collision play important roles for the motion. Here “adjust and try” method is used instead of the calculation. This video was made based on (minute 4:17 - 5:10)