Final answer:
Galileo dropped objects of different masses to demonstrate that they fall at the same rate regardless of their mass.
Step-by-step explanation:
Galileo dropped two objects of different masses from the Leaning Tower of Pisa to demonstrate that objects fall at the same rate regardless of their mass. He measured the time it took for each object to reach the ground to support his conclusion. If the objects were the same size but had different masses, he should have observed that both objects hit the ground at the same time. This result would be the same on the Moon because the acceleration due to gravity is constant for all objects on Earth and the Moon.