“…Example 5.2 (Ball rolling on a spherical surface). Consider a ball of radius r and mass m that is rolling without sliding on the inner side of half a sphere of radius R + r. We can take coordinates (x, y) for the centre of the ball, which moves on a half sphere Σ of radius R, with z = − R 2 − x 2 − y 2 + R and we can take Euler angles for the orientation of the ball, that is, as local coordinates for SO(3) (see [3,Section 5.3] and [23]). The configuration space is SO(3) × Σ.…”