Gyroscopic exercise tool
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This article is about the gyroscopic exercise tool and toy. For the US lottery, see Powerball. For other "powerballs", see Powerball (disambiguation).
A Gyroscopic Exercise Tool is a specialized device used in physical therapy to improve wrist strength, promoting the development of palm, forearm, and finger muscles. It can also be used as a unique demonstration of some aspects of rotational dynamics. The device consists of a tennis ball-sized plastic or metal shell surrounding a free-spinning mass, with an inner heavy core, which can be spun by a short rip string. Once the gyroscope inside is going fast enough, the person holding the device can accelerate the spinning mass to high rotation rates by moving the wrist in a circular motion. The force enacted on the user increases as the speed of the inner gyroscope increases.