Here's why:
* Inertia: Inertia is the tendency of an object to resist changes in its motion. This means it takes effort to start an object moving, or to stop it once it's moving.
* Mass: Mass is the amount of matter in an object.
The more massive an object is, the more inertia it has. This is because there's simply more "stuff" to resist changes in motion.
Examples:
* Pushing a car vs. pushing a bicycle: A car has a much higher mass than a bicycle. You'll need to apply significantly more force to get the car moving, and it will be harder to stop once it's in motion. This is because the car has more inertia.
* Throwing a baseball vs. throwing a bowling ball: A bowling ball has a much higher mass than a baseball. You'll need to use much more force to throw the bowling ball, and it will be much harder to change its direction in mid-flight.
In summary: Mass is the physical quantity that determines how much inertia an object has. The greater the mass, the greater the inertia, and the more resistant the object will be to changes in its motion.
