"A beam is similar to a rod because both have the same geometry - long and slender. However the beam is loaded differently. A rod is subjected to tensile or compressive forces applied in the axial direction. A beam is subjected to transverse forces applied in a perpendicular direction to the longitudinal axis of the long, thin member." p9-1

AXIS
AN IMAGINARY LINE THAT SERVES AS A CENTER OF ROTATION OR A REFERENCE LINE

CROSS SECTION
AN INTERIOR VIEW OF A CROSS-CUT THROUGH AN OBJECT

DISTRIBUTION
A QUANTITY OR PROPERTY THAT IS SPREAD OUT OVER A REGION

NEUTRAL AXIS
IN A BENT BEAM, IT IS THE LINE OF ZERO STRESS BELOW WHICH ALL FIBERS ARE IN TENSION AND ABOVE WHICH THEY ARE IN COMPRESSION.

PURE BENDING

STRESS

STRESS

STRESS DISTRIBUTION

SYMMETRIC CROSS SECTION