Answer to Question #61726 in Classical Mechanics for Brent Garey

Question

A 9 mm bullet ifs fired from from a 9 mm pistol at 300 meters per second, horizontally to the Earth's surface from 4 feet above the Earth's surface.. At the same time, a 9mm bullet was dropped from 4 feet above the ground. Will the 2 bullets hit the Earth's surface at the same time?

Answer 1

Assume no air friction. Thus, the motion of the bullet is the projectile motion. The initial vertical component of velocity is zero for both bullets. Therefore, their time of flight depends only on the initial height. But it is the same for each of them. The answer is “yes”, the 2 bullets will hit the Earth's surface at the same time.