Final answer:
The gravitational force on the rock is greater than that on the paper due to its larger mass. Both the rock and the paper, regardless of their mass, experience the same gravitational field strength and will accelerate at the same rate in a vacuum. Hence, all the options A, B and C are true.
Step-by-step explanation:
In addressing the question concerning the gravitational force acting on a rock and a piece of paper, both held at the same height, we draw upon our understanding of gravitational force and its relationship to mass and gravitational field strength.
A. The gravitational force (F) on an object is given by the equation F = mg, where m is the mass of the object and g is the gravitational field strength (approximately 9.8 m/s2 on Earth's surface). Therefore, the gravitational force acting on the rock (mass = 5 kg) is significantly greater than the force acting on the paper (mass = 4.5 g or 0.0045 kg), since Frock = 5 kg × 9.8 m/s2 and Fpaper = 0.0045 kg × 9.8 m/s2.
B. The gravitational force is directly proportional to the mass of the object: as mass increases, the gravitational force increases linearly.
C. The gravitational field strength g is constant at a given location and altitude above the ground. Thus, at the same height, both the rock and the paper experience the same gravitational field strength.
D. The mass of an object does not affect the gravitational acceleration it experiences. In a vacuum, where air resistance is absent, both the rock and the paper would accelerate at the same rate due to gravity, which is g.