I was recently building an assembly with about 30 parts. There were bearing and shafts, so some of the parts were moving. After it was built I forgot on bit of information. Gravity. How do I include this into my assembly. I had hinges in the wrong places so, some parts were moving down when I wanted them to go up. Here is a simple fulcrum with two spheres. Lets assume the small one weighs 50 lbs and the large one 1 lb. How can I add gravity to show effect. I know I can change material, but my original assembly had numerous parts and several different materials.