1. The problem statement, all variables and given/known data Given, force of constant magnitude, which is always perpendicular to the velocity of the particle & the motion takes place in a plane. What happens to its kinetic energy? Explain. 2. Relevant equations Work energy theorem 3. The attempt at a solution According to work energy theorem, the work done turns out to be zero. This implies that the change in kinetic energy is zero i.e. the kinetic energy is constant.