According to Newton's First Law of Motion, what does it state about bodies in motion?

Newton's First Law of Motion states that a body at rest will remain at rest, and a body in motion will continue in its state of motion at a constant velocity, unless acted upon by an external force. This principle is fundamental in understanding the behavior of objects. It signifies that an object will not change its state (either rest or uniform motion) without an external influence.

This law explains why a spacecraft continues to travel through space without needing constant propulsion, as there are very few forces acting on it. It illustrates the concept of inertia, where an object's resistance to change in its motion is directly linked to its mass.

The other options do not align accurately with this principle. Spontaneous changes in direction, acceleration due to gravity, or coming to a stop without external forces are not concepts supported by this law, as they imply the influence of forces that would indeed alter the state of motion. Understanding this foundational law is crucial for comprehending other concepts in physics, especially in aviation and aerospace engineering.