Past exam of the mathematics course of the University of Cambridge 2014 ia Paper 4 10C Solution Created 2026-09-24 Updated 2026-10-06
For any vector , differentiating its components and the rotating basis gives the rotating-frame derivative formulaApply it twice to the position , with constant angular velocity . The inertial acceleration iswhere dots denote rotating-frame derivatives. Newton's second law therefore becomesThe last terms are the Coriolis force and the force corresponding to centrifugal acceleration.
For the particle on a uniformly rotating inclined plane, choose orthonormal vectors along the horizontal axis and up the slope, and set , the upward normal vector. Then andHere is the normal reaction. The marble is modeled as the smooth sliding particle specified by the printed equations, without an additional rolling constraint. The rotating-frame Coriolis acceleration and centrifugal acceleration are respectivelyThe normal rotating-frame acceleration is zero, so the normal reaction is not generally ; it satisfiesProjecting the same equation onto the two tangential axes gives exactly
Multiply the equations by and and add. The Coriolis force terms cancel, as expected because this force does no work relative to the rotating frame. The normal reaction also does no work along the plane. The conserved quantity is rotating-frame kinetic energy plus gravitational and centrifugal potential energy:This need not be the conserved inertial energy, since the externally driven rotating plane can exchange energy with the particle.