1. The problem statement, all variables and given/known data A 20g rubber is lying on the end of a 30cm long 30g ruler. Determine how far from the rubber you have to support the ruler with your finger to keep the system balanced. 2. Relevant equations I know that I have to calculate the forces which act downwards: the rubber: 20*10^-3kg * 9.81m/s^2 and the ruler: 30*10^-3 * 9.81m/s^2 and then I don't know what to do...Do I have to add them to get the force which is acting upwards? Or how do I get the distance from the rubber to my finger? The solution is 9.0cm.