Two bullets are fired simultaneously parallel to a horizontal plane. The bullets have different masses and different initial velocities. Which one will strike the plane first? a) The fastest one. b) The lightest one. c) The heaviest one. d) The slowest one. e) They strike the plane at the same time.

Therefore, the answer is E. They strike the plane at the same time.

Explanation:

Here, it is seen that the time depends only on acceleration due to gravity (which is a constant) and vertical displacement, and not on velocity of the bullets or mass of the bullets.

Hence, the bullets that are fired simultaneously parallel to the horizontal plane will strike the plane at the same time.

using equation of motion for displacement

s= ut + ¹/₂gt²

here, g is the acceleration due to gravity along y- direction

U along y is 0

s = (0)t + ¹/₂gt²

s=¹/₂gt²

make t the subject of formula =  

conservation of mass

mass before something happens = mass afterwards