Contact and Non-Contact Forces

A FORCE is a push or pull upon an object resulting from its interaction with another object.

There are TWO main types of forces based on whether the objects are in physical contact or not.

Contact Forces

CONTACT FORCES occur when objects must touch each other. Examples include:

• FRICTION: the force that RESISTS motion when the surface of one object comes in CONTACT with the surface of another.
• AIR RESISTANCE: The force exerted on a moving object when it moves through the AIR.
• TENSION IN ROPES: The force transmitted through a STRING, rope, cable, or wire when it is pulled tight by forces acting from opposite ends.
• NORMAL CONTACT FORCE: The support force exerted upon an object that is IN CONTACT with another stable object.

Non-Contact Forces

NON-CONTACT FORCES can act at a distance without physical contact. They include:

• MAGNETIC FORCE: The attraction or repulsion between MAGNETS.
• GRAVITATIONAL FORCE: The force of attraction between all MASSES in the universe.
• ELECTROSTATIC FORCE: The force between CHARGED particles or objects.