Q1: Hollow shafts can be made as strong as solid shafts by making the twisting moments of both the shafts same. Shafts made by __________ have residual stresses.

ANS:B - cold rolling

Cold rolling is a metalworking process that occurs at room temperature, typically after the metal has been annealed (heat-treated). In this process, the metal is passed through rollers at room temperature, which compress and shape it into the desired form. Cold rolling can be used to reduce the thickness of a metal sheet or to produce various shapes such as bars, rods, or tubes. During cold rolling, the metal undergoes plastic deformation, where it is shaped without reaching its melting point. This process increases the strength and hardness of the metal while maintaining its ductility. Cold rolling also improves the surface finish and dimensional accuracy of the metal. One advantage of cold rolling is that it allows for tighter tolerances and finer surface finishes compared to hot rolling, where the metal is rolled at elevated temperatures. Additionally, cold rolling can produce work-hardened surfaces, which further enhances the mechanical properties of the metal. Overall, cold rolling is widely used in the manufacturing industry for producing high-quality metal products with precise dimensions and improved mechanical properties.