Final answer:
In projectile motion, both bullets will hit the plane at the same time because gravity accelerates all objects downwards at the same rate, regardless of mass or horizontal velocity.
Step-by-step explanation:
The question relates to the concept of projectile motion in physics. When two bullets are fired simultaneously parallel to a horizontal plane, with different masses and velocities, the one that hits the plane first is determined not by these factors but by the effects of gravity. According to the physics principle of projectile motion, all objects in free fall near the Earth's surface accelerate downwards at the same rate due to gravity, regardless of their mass or horizontal velocity. Thus, both bullets will hit the plane at the same time if they are fired from the same height.