SOLUTION

External Load

• All forces acting on a body, including the reactive forces caused by supports, are considered external forces.
• These forces are classified as surface forces and body forces.
• A surface force is concentrated when it acts at a point, but it may also be distributed over a finite area.
• A body force acts on a volumetric element rather than on a surface and is attributable to fields such as gravity and magnetism.
• When a body is subjected to fluid pressure is an example of external static hydrostatic loading, which is arising from fluid pressure.
• Bearing subject to external dynamic loading or component subjected to continuous fluctuating loading are the cases of external loads arising from service conditions.

Cohesion force is a force of attraction between similar types of molecules which considered to be internal to the system. Hence those arising from cohesion are not considered as external loads.