What are the external forces that cause the elastic deformation of materials? Describe those forces that change the form and size of materials.

External forces and deformation

External forces that cause elastic deformation of materials are called loads. These forces can be:

• Tensile forces: These forces pull on the material, stretching it and increasing its length. Imagine pulling a rubber band in opposite directions.
• Compressive forces: These forces push on the material, squeezing it and decreasing its length. Think about crushing a can.
• Shearing forces: These forces act parallel to the surface of the material, causing layers to slide past each other. Cutting with scissors is an example of shear.
• Torsional forces: These forces twist the material around an axis. Twisting a screwdriver to tighten a screw involves torsion.
• Bending forces: These forces cause a material to curve. Bending a ruler applies bending forces.

These forces change the form and size of materials by deforming them. If the force is within the elastic limit, the material will return to its original shape once the force is removed.