Work = F-sub-parallel times d

When a point particle moves along a path under the influence of a force, the work done on the particle by the agent of the force is the component of the force along the path times the length of the path.

Notes:
  1. The component of the force along the path must be constant.
  2. The component of the force along the path is to be considered positive when it is in the direction of the motion of the particle, and negative when it is in the direction opposite to that of the motion of the particle.
  3. This equation represents one form of the definition of work.