Which property of an object changes when an unbalanced force acts on it?

A. Mass

B. Inertia

C. Velocity

D. Temperature

The answer is velocity; this is because if an object has a net force acting on it, it will accelerate. The object may speed up, slow down or change direction. An unbalanced force acting on an object changes its speed and/or direction of motion, therefore; the unbalanced force is an unopposed force that causes a change in motion.