Which law states that an object at rest and an object in motion remain in that state unless acted upon by an unbalanced force?

Which law states that an object at rest and an object in motion remain in that state unless acted upon by an unbalanced force?

• A. Newton's First Law of Motion
• B. The Law of Gravity
• C. Newton's Third Law of Motion
• D. Newton's Second Law of Motion

Answer: (A)

Inertia is the tendency of an object to resist changes to its motion. An object at rest stays at rest because there’s no net external force to start it moving; an object moving in a straight line at constant speed keeps moving that way unless a net external force changes its motion. When the net force acting on an object is zero, its velocity remains constant, which is exactly what this statement describes. This idea is Newton’s First Law, often called the Law of Inertia. Think of a hockey puck gliding on a nearly frictionless surface: it would keep going straight at the same speed unless a force—like friction, a collision, or a push—acts on it to slow it down, speed it up, or change its direction. It captures the default behavior of objects: they resist changes to how they are already moving. The other Newton laws describe different ideas. Gravity is a force that can cause acceleration when it acts on an object, rather than simply stating that motion persists without unbalanced forces. The second law links net force to acceleration with the equation F = ma. The third law describes how forces come in action-reaction pairs.

Inertia is the tendency of an object to resist changes to its motion. An object at rest stays at rest because there’s no net external force to start it moving; an object moving in a straight line at constant speed keeps moving that way unless a net external force changes its motion. When the net force acting on an object is zero, its velocity remains constant, which is exactly what this statement describes. This idea is Newton’s First Law, often called the Law of Inertia.

Think of a hockey puck gliding on a nearly frictionless surface: it would keep going straight at the same speed unless a force—like friction, a collision, or a push—acts on it to slow it down, speed it up, or change its direction. It captures the default behavior of objects: they resist changes to how they are already moving.

The other Newton laws describe different ideas. Gravity is a force that can cause acceleration when it acts on an object, rather than simply stating that motion persists without unbalanced forces. The second law links net force to acceleration with the equation F = ma. The third law describes how forces come in action-reaction pairs.