Final answer:
Gravity on the Moon is less than on Earth due to the Moon's lower mass and the larger distance from Earth's center. Newton's law of gravitation explains not only why objects fall to Earth but also the Moon's orbit around Earth, with gravity decreasing with the square of the distance.
Step-by-step explanation:
Using Newton's universal law of gravitation, we can understand why gravity on the Moon is less than the gravity on Earth. The law states that the gravitational force between two masses is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. Since the Moon has less mass than Earth and the gravitational acceleration at its surface is 1.625 m/s², which is less than Earth's 9.80 m/s², the force of gravity is weaker on the Moon. Your mass remains the same regardless of location, but your weight, which is the force of gravity acting on your mass, is different because it's dependent on the local acceleration due to gravity.
Newton also observed that the same law of gravitation that explains why an apple falls to the ground on Earth can predict the Moon's acceleration towards Earth in its orbit. The distance factor plays a significant role; as the Moon is about 60 Earth radii away, the gravitational pull it experiences from Earth is significantly less than that on the surface of Earth. This results in an acceleration that is about (1/60)² or 1/3600 times weaker than that experienced by the apple, aligning with the observed acceleration of 0.00272 m/s² for the Moon in its orbit.