Procedure: For each of the parts (tabs) below, be sure to click on the Mass Labels, Forces from Objects, and Level. Also click on Ruler. TAB 1 "Intro": Apply the concepts of center of mass, torque and mechanical equilibrium to achieve perfect mechanical equilibrium for the following situations (note: the "Level" arrows become green when the seesaw is perfectly balanced), then record the position of each object. 1. One fire extinguisher on the left and the trashcan on the right. 2. Two fire extinguishers on the left and the trashcan on the right. 3. One fire extinguisher and the trash can on the left and a fire extinguisher on the right