What is inertia?

What is inertia?

• A. The force that keeps an object moving in a straight line
• B. The energy possessed by a moving object
• C. The tendency of an object to resist a change in motion or at rest
• D. The rate of change of velocity

Answer: (C)

Inertia is the tendency of an object to resist any change to its motion or to stay at rest. Mass is the measure of that resistance. For a skier, inertia explains why a rider keeps moving in a straight line at the current speed unless a force acts to change it—like edging or turning to steer, or gravity and friction on a slope altering motion. Inertia isn’t a force you feel pushing you forward; it’s the natural resistance to changes in velocity. The rate at which velocity changes is acceleration, and the energy a moving object has is kinetic energy—both related ideas, but they describe different things, not inertia itself.

Inertia is the tendency of an object to resist any change to its motion or to stay at rest. Mass is the measure of that resistance. For a skier, inertia explains why a rider keeps moving in a straight line at the current speed unless a force acts to change it—like edging or turning to steer, or gravity and friction on a slope altering motion. Inertia isn’t a force you feel pushing you forward; it’s the natural resistance to changes in velocity. The rate at which velocity changes is acceleration, and the energy a moving object has is kinetic energy—both related ideas, but they describe different things, not inertia itself.