posted by Brandon .
An unknown mass is suspended by a string from
one end of an uniform stick which has a mass of
120 g. In order to balance the stick, it must be
supported one third of its length away from the mass. the unknown mass is therefore?
Let m be the unknown mass and M be the stick's mass. Stick length = L . The center of mass is L/6 from the fulcrum. The total moment about the fulcrum is zero.
m*g*(L/3) = M*g*(L/6)
m = M/2 = 60 g