Forced precession in a spinning wheel supported on a rotating pivot

•We analyzed a spinning wheel of which the pivot is not fixed but forced to rotate.•We introduced a fourth Euler angle related to the motor (forced precession).•We investigated two types of joints between rotating arm and wheel's axle.•We clarified the energy exchange between the experimentist (motor) and the gyro.•We explained the biomechanics involved in Laithwaite's classical gyro experiment.

This paper deals with the mechanics involved in a spinning wheel of which the pivot is not fixed as usual but is forced to rotate along the circumference of a circle on the horizontal plane. The usual Euler equations are extended so that, in addition to the three well-known rotations (Euler angles), they also include a fourth one related to the rotation of the motor that induces the forced precession. This study aims at offering a first insight in one of the renowned Laithwaite's experiments. The derived theoretical expressions are accompanied by computer simulation.