Final answer:
The force of gravity decreases as the distance between two objects increases, which is explained by Newton's law of universal gravitation. For a red giant star expanding in size, the surface gravity becomes weaker. Two objects of different masses experience the same gravitational force, but the one with lesser mass will accelerate more.
Step-by-step explanation:
The force of gravity between two objects decreases as the distance between them increases. According to Newton's law of universal gravitation, gravity is inversely proportional to the square of the distance between the centers of the two objects. This means that if the distance is doubled, the gravitational force decreases to one-fourth; if tripled, it decreases to one-ninth. For a red giant star, as its size increases and its outer layers expand, a point on its surface becomes farther from the center, leading to a weaker gravitational pull at that point. Consequently, the escape velocity—the speed needed to break free from the star's gravitational hold—also decreases. When considering two objects, such as asteroids with different masses, attracting each other gravitationally, Newton's third law tells us that they will experience the same gravitational force, but the one with the lesser mass will