Final answer:
When identical guns fire identical bullets horizontally at the same speed, the vertical motion is independent of the horizontal motion. The horizontal velocity remains constant and unaffected by gravity or vertical motion, assuming ideal conditions.
Step-by-step explanation:
When identical guns fire identical bullets horizontally at the same speed, the vertical motion of the bullets is independent of their horizontal motion. This is because the vertical motion of a falling object is influenced by gravity only, not by any horizontal forces. The horizontal velocity of the bullets remains constant and unaffected by their vertical motion or gravity, assuming ideal conditions without air resistance.
For example, if two identical bullets are fired horizontally, both bullets will travel the same horizontal distance between flashes of a strobe light. This is because there are no additional forces acting on the bullets in the horizontal direction after they are fired.
However, it is important to note that in the real world, air resistance will affect the speed of the bullets in both horizontal and vertical directions.