Earth's mass is approximately 81 times the mass of the moon. if earth exerts a gravitational force of magnitude f on the moon, the magnitude of the gravitational force of the moon on earth is

The answer is 1F. The gravitational force between two objects is equal. The earth pulls on the moon with a force equivalent in magnitude (but opposite in direction) to the force of the moon's attraction on the earth. This does not unavoidably mean that the accelerations are similar, for the reason that of the different masses of the objects, but for this question, it would be the same amount of force which is F. Based on the formula: F = G (M1M2) / r^2 (newton's law of universal gravitation)