Marion, J.B. (1970) Classical Mechanics. Academic Press, New York, 65.
TITLE: The Work of a Normal Force
AUTHORS: Pirooz Mohazzabi
ABSTRACT: It is shown that an impulsive force acting on a particle perpendicular to its velocity vector cannot change its direction of motion without increasing its kinetic energy. If the particle’s kinetic energy is to remain unchanged, the impulsive force must have a component in the direction opposite to the direction of motion. This situation is also realized in the case of a continuous force acting perpendicular to the velocity vector of the particle, when the particle's motion is viewed as a sequence of infinitesimal steps.