Final answer:
A diagram representing the gravitational forces between Earth and a satellite should show equal and opposite arrows pointing towards each other's center, according to Newton's law of gravitation and his third law of motion.
Step-by-step explanation:
The question centers around identifying a diagram that best represents the gravitational forces between a satellite and Earth. To depict this accurately, one must take into account Newton's law of gravitation, which states that any two bodies attract each other with a force proportional to the product of their masses and inversely proportional to the square of the distance between their centers. This gravitational force (Fg) is calculated using the formula F = G * (m1 * m2) / r^2, where G is the gravitational constant, m1 and m2 are the masses of the two objects, and r is the distance between the centers of the two masses.
An ideal diagram would show the Earth and the satellite with an arrow representing the force of gravity pointing towards each other's center. The magnitude of this force should be equal on both Earth and the satellite, following Newton's third law, which states that for every action, there is an equal and opposite reaction. Moreover, the diagram could also depict that the gravitational pull causes the satellite to fall towards the Earth, but due to its horizontal velocity, it falls around the Earth, thus staying in orbit.
The gravity gradient mentioned relates to the slight difference in gravitational force experienced at different parts of the satellite due to its extended size, which causes it to orient itself with the longer axis perpendicular to its orbital path. However, when considering the overall gravitational interaction between Earth and a satellite, a simple two-object diagram with mutual force arrows is most accurate.