Which factor primarily influences the trajectory of falling objects?

The trajectory of falling objects is primarily influenced by air resistance and gravity. Gravity is the force that pulls objects towards the Earth, causing them to accelerate downwards at approximately 9.81 m/s². This acceleration is constant regardless of the objects' weight, although heavier objects experience a greater gravitational force.

Air resistance, also known as drag, acts in the opposite direction to the motion of the falling object. It is affected by factors such as the object's speed, cross-sectional area, and shape. As an object falls and its velocity increases, air resistance also increases, which can significantly alter its trajectory, especially for lighter objects or those with a large surface area.

Together, air resistance and gravity determine how quickly an object falls and the nature of its path as it descends. In a vacuum, where there is no air resistance, all objects, regardless of their mass, would fall at the same rate; however, in the real world, both gravity and air resistance must be considered to fully understand the falling object's motion.