The work done against a force is the negative of the work done by the force The kinetic energy of a particle is the product of one-half its mass and the square of its speed, for non-relativistic speeds

The kinetic energy of a system is the sum of the kinetic energies of all the particles in the system The infinitesimal increment of work done by a force, acting over an infinitesimal displacement, is the dot product of the force and the displacement

work — done when a force acts on something that undergoes a displacement from one position to another. kinetic energy — energy of motion, one-half an object’s mass times the square of its speed. kinetic energy of a particle — the product of one-half its mass and the square of its speed, for non-relativistic speeds. kinetic energy of a system — the sum of the kinetic energies of all the particles in the system.