When two objects of different masses are dropped from the same height, what primarily influences their time of descent in a vacuum?

The time of descent for two objects dropped from the same height in a vacuum is primarily influenced by gravity. In a vacuum, there is no air resistance to impede the motion of the objects, meaning they are solely affected by gravitational force. According to the principle established by Galileo and later confirmed by Newton, all objects, regardless of their mass, will accelerate towards the Earth at the same rate due to gravity. This acceleration is approximately (9.81 , \text{m/s}^2) near the Earth's surface.

Since both objects are dropped from the same height and experience the same gravitational acceleration, they will hit the ground simultaneously if dropped at the same time. The mass of the objects does not affect the rate of fall in a vacuum, nor does the height of the drop influence the time of descent, as both will take the same amount of time to fall that height because of the constant acceleration due to gravity. Thus, gravity is the definitive factor determining the descent time in this scenario.