Hello. I need help clearing up who's gaining potential energy and who's losing potential energy from an particular object perspective. And, from that object perspective, whether the object doing positive work or negative work. [tex]W = \int \vec F \cdot d\vec x[/tex] [tex]\Delta U = -W[/tex] Question 1: From the left-hand perspective, the left-hand moved in the positive x-direction and it applied a force in the positive x-direction therefore... it did positive work on the right-hand. Is this correct? Question 2: continuing from question 1 If the left-hand did positive work on the right-hand, does this mean that the left-hand has lost potential energy? Question 3: continuing from question 2 If the left-hand has really lost potential energy, how come when the left-hand "lets go" (stop applying a force in the positive x-direction), the left-hand want to naturally accelerates in the negative x-direction. Doesn't accelerating mean that the left-hand is converting it's potential energy into kinetic energy? Where does it get that energy from? --- Question 4: From the right-hand perspective, the left-hand is moving in the positive x-direction, but it's also moving against the electric field from the right-hand so... the work done by the right-hand on the left-hand is negative. Question 5: continuing from question 4 The left-hand gains potential energy while the right-hand loses potential energy. Is this correct? Why/why not? Also... what hell does it mean for the right-hand to lose/gain potential energy? --- Thanks in advance!