Here's why:
* Inertia is the tendency of an object to resist changes in its motion. This means it wants to stay at rest if it's at rest, and it wants to keep moving at a constant velocity if it's already moving.
* Mass is a measure of the amount of matter in an object.
The greater the mass of an object, the more inertia it has. This is because a more massive object has more matter, and therefore more resistance to changes in its motion.
Examples:
* A bowling ball has more mass than a tennis ball. If you push both with the same force, the bowling ball will be harder to move and will take longer to accelerate because it has more inertia.
* A car has more mass than a bicycle. It takes more force to stop a car than a bicycle because the car has more inertia.
In summary, mass and inertia are directly proportional. The more massive an object is, the greater its inertia.
