Mobile (sculpture)

A mobile is a type of kinetic sculpture constructed to take advantage of the principle of equilibrium. It consists of a number of rods, from which weighted objects or further rods hang. The objects hanging from the rods balance each other, so that the rods remain more or less horizontal. Each rod hangs from only one string, which gives it freedom to rotate about the string.

The sculptor Alexander Calder is well known for his mobiles. Calder is credited with inventing the mobile in 1931, although it was named by Marcel Duchamp. Mobiles are also popular in the nursery, where they hang over cribs to give infants something to entertain them and give them external visual stimulus.

Mobiles have inspired many composers, including Morton Feldman who was inspired by Calder to create mobile-like indeterminate pieces.