Question

An artist wishes to construct a moon-and-star mobile. If the star on the lower left has a mass of 200 grams, what are the masses of the other stars and moon

Answer 1

If the star on the lower left at distance d from the fulcrum lies in the same horizontal plane with the other stars and moon at distance D from the fulcrum, the mass of the stars and moon is

$$M=m\frac{d}{D}$$