Why is the First Law of Motion important?

Inertia, as the First Law says, is the resistance to any change in motion. The law states that every object at rest stays at rest and one in motion stays in motion unless acted on by a force. For example, in a bus that starts or stops suddenly, your body resists the change, making you feel pushed ba

No, that's a common misconception about force in any object at rest. According to Newton's First Law, zero acceleration means zero net force. That does not mean zero force. A book on a table is at rest because two forces act on it. Gravity pulls it down. The table exerts an equal upward normal force