Answer
(a) $13J$
(b) $20J$
Work Step by Step
(a) It is given that the particle is at rest at point B and has potential energy $25J$ at this point. Thus, the total potential energy of the particle is $25J$. At point A, the kinetic energy of the particle is $12J$. Thus, the potential energy of the particle at point A is $25J-12J=13J$.
(b) It is given that at point C, the particle has potential energy $5J$. Thus, the kinetic energy of the particle at point C is $25J-5J=20J$
