At time ti , the kinetic energy of a particle is J and the potential energy of the system to which it belongs is J. At some later time tf , the kinetic energy of the particle is J.
(a) If only conservative forces act on the particle, what are the potential energy and the total energy of the system at time tf ?
(b) If the potential energy of the system at time tf is 5.00 J, are any non-conservative forces acting on the particle?
(c) Explain your answer to part (b).