Balancing Act

1943JunePSSeventy-five years ago this month, the June 1943 issue of Popular Science showed how to do this seemingly impossible balancing act. The hammer is suspended by a string in the middle, with the end of the handle exerting an upward force on the end of the ruler. Since the center of gravity is under the table, the ruler stays in place.

This simple stunt could be the basis for an elegantly simple science fair project regarding leverage.