A roly-poly toy, roly-poly doll, round-bottomed doll, tilting doll, tumbler, wobbly man, or wobble doll is a round-bottomed toy, usually egg-shaped, that tends to right itself when pushed at an angle, and does this in seeming contradiction to how it should fall.
Different toy manufacturers and different cultures have produced different-looking roly-poly toys: the okiagari-koboshi (起き上がり小法師, "take a spill, get up, and arise"), Kokeshi doll and some types of Daruma doll of Japan, the nevаlyashka (неваляшка, "untopply") or van'ka-vstan'ka (ванька-встанька, "Ivan-get-up") of Russia, and Playskool's Weebles. Such toys' self-righting characteristics have come to symbolize the ability to have success, overcome adversity, and recover from misfortune.[1]
Traditional Chinese examples (called 不倒翁, bù dǎo wēng) are hollow clay figures of plump children, but "many Chinese folk artists shape their tumblers in the image of clownish mandarins as they appear on stage; in this way, they mock the inefficiency and ineptitude of the bureaucrats".[2]
Fisher-Price, a well-known toy manufacturer, recommends roly-poly toys for small children just developing motor skills; a child can bat at it without its rolling away.[3]
The toy is typically hollow with a weight inside the bottom hemisphere. The placement of this weight is such that the toy has a center of mass below the center of the hemisphere, so that any tilting raises the center of mass. When such a toy is pushed over, it wobbles for a few moments while it seeks the upright orientation, which has an equilibrium at the minimum gravitational potential energy.
