Here's why:
* Contact forces require physical contact between objects to occur.
* Examples:
* Normal force: The force that supports an object resting on a surface.
* Friction: The force that opposes motion between surfaces in contact.
* Tension: The force transmitted through a string, rope, or cable when pulled taut.
* Air resistance: The force that opposes the motion of an object through air.
In contrast to contact forces, there are non-contact forces that act between objects that are not touching, such as gravity and magnetism.
