Which of the following is NOT a force acting on ballistics?

The forces that act on a projectile in motion are critical to understanding its trajectory and behavior. Wind, gravity, and air resistance are all external forces that influence the path of a projectile.

Gravity is the force that pulls the projectile towards the Earth, ensuring that it will always follow a curved path when in motion. Air resistance, also known as drag, opposes the projectile's motion through the atmosphere, impacting its speed and distance traveled. Wind adds another layer of complexity as it can alter the projectile's path and influence its accuracy.

Acceleration, however, is not a force, but rather a measure of the change in velocity of an object over time. While acceleration can result from the impact of forces being applied to a projectile (such as thrust when fired, or the effects of gravity), it itself is not an external force affecting the projectile's motion. Thus, among the options provided, 'acceleration' stands out as the element that does not classify as a force acting on ballistics.