Resistance offered to the movement of one body past
another body with which it is in contact.
of friction depends on the nature of the contact surfaces
and on the magnitude of the force pressing the two
bodies together, but not on the surface area of the
The coefficient of friction is the
ratio of the force necessary to move one body horizontally
over another at a constant speed to the weight of
Fluid friction, observed in the flow of
liquids and gases, is minimized in airplanes by a
modem, streamlined design (Aerodynamics).