Different types of forces

A list of some different types of forces that are encountered regularly in physics is shown below.

Normal force:

Definition: The normal force is the force exerted by a surface on an object.

Direction: Perpendicular to and away from the surface.

Symbol: FN

Example:  Put a book on a table. The table exerts a normal force on the book which prevents the book from falling down.

Frictional force:

Definition: The frictional force is the force that resists sliding motion between surfaces.

Direction: Parallel to the surface and opposite the direction of sliding

Symbol: Ff

Example: You put a book on the floor and you kick it so it slides on the floor. The book will eventually stop sliding because of the force of friction.


DefinitionThe weight is the force caused by the gravitational attraction between two objects. Generally this force happens between the earth and an object.

Direction: Straight down toward the center of the earth.

Symbol: Fg

Example:  Every time you jump into the air, your weight is the force that keeps pulling you down.


Definition: The tension is the pull exerted by a rope, cable, or string when attached to an object and stretched tight.

Direction: Away from the object or the point of attachment and parallel to the rope, cable, or string.

Symbol: FT

Example: Wrap a rope around a box and using your hand to drag the box with the rope. A tensional force will be created along the rope.


Definition: The thrust is the force that can move objects such as air planes, rockets, cars, or people.

Direction: Same direction as the acceleration of the objects. 

Symbol: Fthrust


Definition: The push or pull a spring exerts on an object

Direction: Opposite the displacement of the object. 

Symbol: Fsp

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