How many internal forces do we have in structural members and what are they? For what type of deformation each one of them would be responsible? You can make some drawings to illustrate your answers. Solution There are types 4 of internal forces.They are gravity forces, magnetic force, electrical force, and spring force. gravitational force is responsible to pull objects towards center of the earth.Magnetic forces doesnot cause any deformation but are responsible for attracting iron objects towards each other. Spring force have deformation towards themselves..