The Normal Force

leonardo statue

The Normal force is a force that counterbalances, or opposes the force of gravity for an object resting on a surface.

The force of gravity, Fg always points down, (towards the center of the Earth), the Normal Force always points in a direction opposite to the Force of Gravity.

The symbol for the Normal Force is FN and, like all forces it is also measured in Newtons.

Consider the following situations:

1. FN acting on an object placed on a level surface

This is a photo of the statue of Leonardo Da Vinci, in Milan, Italy, resting on its pedestal:

Photo Credits (L. Lista 2012)






If the image of the staute is removed we are left with the diagram on the right which shows the vectors identifying the FBD proper.  Therefore the Free Body diagram for this statue could look like this.

note Note how FN and Fg are collinear (along the same line of action).  They are equal in magnitude but opposite in direction


leonardo fbdleonardo fbd2

 noteConsider now the case where the statue is slanted at a certain angle....

note Note that, while the force of gravity Fg is still acting perpendicularly down towards the center of the earth.

noteThe normal force FN is now acting up but perpendicular to the inclination plane

leonardo fbd tipping  leonardo fbd tippingFBD2