The semirigid rotor can also be referred to as a teetering or seesaw rotor. This allows the blades to flap together in opposite motions like a seesaw. Some of the most common constructions were the carousel, sphere, seesaw, rocket, bridge, etc. The most common playground design of seesaw features a board balanced in the center. In the seesaw fighting on decks, the allies prevailed. An equation is analogous to a weighing scale, balance, or seesaw. Within the seesaw mechanism, the sterile neutrinos become superheavy without affecting physics at low energies. The name "seesaw" comes from the observation that it looks like a playground seesaw. There was a seesaw battle taking place at Area Flat Top. The game began as a seesaw affair between the two teams. In 1973, Gavin replaced Ken Howard in the Broadway musical "Seesaw" opposite Michele Lee. He leaves and Garbo falls off the seesaw. This is the point of the name "seesaw" of the mechanism. In 1985, Hilary Cosell's book "Woman on a Seesaw" was published by G.P. Putnam's Sons. Her last hit was from their second collaboration in 1973, "Seesaw".