The first step is to draw a free-body diagram of the object or system in question. This will help visualize all the external forces acting on the object and determine which are relevant to finding the internal forces.
The three equations used are the equilibrium equations: ΣFx=0, ΣFy=0, and ΣM=0. These equations are derived from Newton's laws of motion and are used to solve for unknown internal forces.
To identify unknown internal forces, one must first draw a free-body diagram and apply the equilibrium equations. Then, the internal forces can be determined by solving for the unknowns using algebraic methods or with the help of a computer program.
Some common types of internal forces include tension, compression, shear, and bending moments. These forces can be caused by various external loads such as weight, wind, or applied forces.
Internal forces play a crucial role in the stability and strength of a structure. If the internal forces are not balanced, the structure may experience deformation or failure. It is important to accurately determine internal forces in order to design a safe and stable structure.