Final answer:
The tightening of a guitar string is an example of tensile stress, which is associated with the forces that cause the elongation of the string and depends on the material's properties such as elasticity and tensile strength.
Step-by-step explanation:
The tightening of a guitar string is an example of tensile stress. This type of stress is associated with the stretching of an object and is defined as force per unit area leading to an object's elongation. As explained in Figure 7.11, work is done to deform the guitar string, storing potential energy that will be converted to kinetic energy as the string oscillates back and forth.
Thin nylon, thicker nylon, and steel guitar strings exhibit different amounts of deformation for the same applied force. This indicates different 'k' values or elastic moduli for different materials, which means that stiffer strings (such as steel) will stretch less than more elastic strings (like thin nylon) under the same force. However, if the deformation is kept within a small range, the strings will return to their normal lengths once the force is removed. Hence, the elasticity and tensile strength of the material of the strings are essential for their performance and longevity.