Final answer:
If air resistance is negligible, all objects fall with the same constant acceleration due to gravity, independent of their mass. This principle applies universally, not just on Earth, as shown by experiments conducted in a vacuum and historical demonstrations like those on the Moon.
Step-by-step explanation:
When discussing gravity and the acceleration of objects in its presence, one important principle is that in the absence of air resistance, all objects fall with the same constant acceleration, regardless of their mass. This seems counterintuitive since we often observe lighter objects falling more slowly than heavier ones due to the effects of air resistance. However, the phenomenon of objects falling at the same rate in a vacuum was famously demonstrated by astronaut David R. Scott on the Moon, where he showed that a hammer and a feather drop at the same rate when air resistance is negligible. This principle is not unique to Earth, as it applies anywhere in the universe where gravity is present. Whether in a laboratory, on the Moon where gravity is only 1.67 m/s², or on Earth with gravity at approximately 9.81 m/s², the acceleration due to gravity is constant for all objects in a vacuum. This was one of the groundbreaking discoveries made by Galileo Galilei, who debunked the long-held belief that heavy objects fall faster than light ones.