Revival of the jumping disc

Snap discs made of bimetal have many technical applications as thermostats. Jumping discs are a toy version of such snap discs. Besides giving technical information, we describe physical investigations. We show especially how, through simple measurements and calculations, you can determine the initial speed (∼3.5 m s −1 ), the acceleration (∼30 000 m s −2 ) and the lower and upper snap temperature (∼31; ∼99 °C). High speed videos give even deeper insight into the jump.