Inertia

Inertia is the resistance of a body to change its state of motion.

• A body at rest wants to be at rest
• A body in motion wants to be in motion

Have you experienced jerk when brakes are suddenly applied to the vehicle?

This happens because initially the car was in motion; the body was also in motion. Later, due to the application of brakes, the car came to rest; but the body due to its inertia still wants to be in motion. Therefore, the body doesn’t come to rest at once and experiences jerk.

Galileo’s Law of Inertia

• Aristotle’s Law was falsified by Galileo. Galileo corrected Aristotle’s law saying “An external force is required to keep a body in motion, only if resistive forces are present”