A person on a swing, or a pendulum, that is pulled away to its maximum displacement then released will not return to that same exact location on its return swing because
a. friction and air resistance will take away some of the momentum of the moving object (or person).
b. the law of conservation of energy is only a theory.
c. the mechanical energy of the movement is equal to the kinetic energy minus the potential energy and the potential energy has changed.
d. unless the time of the period (the movement from one area of maximum displacement to the other area of