An object at rest will remain at rest unless acted upon by an unbalanced, outside force.

An object at rest will remain at rest unless acted upon by an unbalanced, outside force.

• A. Newton's 1st law of motion
• B. Bernoulli's principle
• C. Newton's 2nd law of motion
• D. Coanda effect

Answer: (A)

This statement reflects inertia—the tendency of an object to resist changes in its motion. An object at rest will stay at rest unless a net external (unbalanced) force acts on it, and a nonzero net force would cause acceleration, changing its motion. If all forces cancel out, there is no acceleration, so the object remains in its current state (still at rest). This idea is the essence of Newton's first law. Bernoulli's principle is about pressure changes in moving fluids, not about an object's state of rest. The Coanda effect describes a jet's tendency to follow a nearby surface due to pressure differences, also not about the rest state. Newton's second law links net force to acceleration (F = m a), which is related but describes how motion changes under a net force; the given statement most directly expresses inertia and the condition of rest from the first law.

This statement reflects inertia—the tendency of an object to resist changes in its motion. An object at rest will stay at rest unless a net external (unbalanced) force acts on it, and a nonzero net force would cause acceleration, changing its motion. If all forces cancel out, there is no acceleration, so the object remains in its current state (still at rest). This idea is the essence of Newton's first law.

Bernoulli's principle is about pressure changes in moving fluids, not about an object's state of rest. The Coanda effect describes a jet's tendency to follow a nearby surface due to pressure differences, also not about the rest state. Newton's second law links net force to acceleration (F = m a), which is related but describes how motion changes under a net force; the given statement most directly expresses inertia and the condition of rest from the first law.