* Friction: Friction is a force that opposes motion between two surfaces in contact. The rougher the surfaces, the more friction there is.
* Weight: When someone sits on the mat, their weight is added to the mat's weight. This increased weight increases the force pressing the mat against the floor.
* Increased Friction: The heavier the mat, the greater the force of friction between the mat and the floor. This makes it much harder to drag the mat.
In simple terms:
1. Empty Mat: The mat only has its own weight, creating a small force of friction with the floor.
2. Person on the Mat: The person adds their weight, making the total weight much heavier. This heavier weight creates much more friction, making it harder to move the mat.
Think of it like this: Imagine trying to push a heavy box across the floor. It's much easier to push an empty box than a box filled with heavy objects. The same principle applies to dragging a mat.