Newton's First Law of Motion states which of the following?

Correct Answer: Option A — A body in a state of rest tends to remain at rest, and a body in motion continues to stay in motion at a constant speed, unless acted upon by some external force.

Newton's First Law, the Law of Inertia, dictates that an object's state of motion remains unchanged unless acted upon by an external unbalanced force. This fundamental principle of classical mechanics is essential for understanding rotor dynamics and the behavior of rotating machinery components within a gas turbine engine assembly.