Final answer:
The gravitational force between Pluto and Charon is attractive. Neither has a greater gravitational force over the other; they exert equal and opposite forces. The gravitational acceleration can be calculated using the universal gravitational constant, masses, and distance between the planetary bodies.
Step-by-step explanation:
The gravitational force between two objects is always attractive; hence, between Pluto and Charon, the force is attractive as well. Since gravitational force is mutual and equal according to Newton's Third Law of Motion, neither Pluto nor Charon exerts a greater gravitational force; they exert equal and opposite forces on each other. Looking further into the comparison with Neptune and Uranus, when calculating gravitational acceleration, we must use the universal gravitational constant G, which is 6.674 × 10-11 N·m²/kg2. Using this constant and the masses of the celestial bodies involved, we can find the acceleration due to gravity that each exerts on the other.