Final answer:
The elevation knob on the M4 Rifle is adjusted to compensate for gravity, affecting the bullet's trajectory and accuracy for targets at different ranges.
Step-by-step explanation:
The question pertains to the adjustments of gun sights on an M4 Rifle in relation to physics, specifically projectile motion. When the elevation knob on the M4 Rifle is adjusted, it compensates for the effects of gravity on the bullet's trajectory. This ensures that the point of aim is accurate for a specific range.
For instance, if a gun is sighted to hit targets at the same height as the gun and 100.0 m away, the bullet will drop due to gravity when aimed at a target 150.0 m away, hitting lower than the sighted point of aim. The muzzle velocity, which in this case is 275 m/s, significantly affects this drop. A higher muzzle velocity means the bullet will travel faster and will be less affected by gravity over the same distance, thus hitting closer to the point of aim.
Air resistance, another important factor, also acts on the bullet, slowing it down and impacting its trajectory. The higher the air resistance, the more the bullet will slow down, which could cause it to hit even lower than anticipated at longer distances.