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Inertia

Definition

Inertia is the tendency of an object to resist changes in its motion. It refers to the property of matter that makes objects continue moving in a straight line or stay at rest unless acted upon by an external force.

Analogy

Imagine you're sitting on a skateboard and someone pushes you from behind. If you have a lot of inertia, it will be harder for the push to change your speed or direction. But if you have less inertia, even a small push can make you move quickly.

Related terms

Mass: Mass is the amount of matter in an object. Objects with more mass have more inertia.

Newton's First Law: Also known as the law of inertia, it states that an object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and direction unless acted upon by an external force.

Momentum: Momentum is the product of an object's mass and velocity. It is related to inertia because objects with more momentum are harder to stop or change their motion.