Q1: A dense structure of grinding wheel is not used for the

ANS:A - ductile material.

Ductile materials are those that can undergo significant plastic deformation before fracturing. When subjected to tensile stress, ductile materials exhibit a significant elongation or deformation without undergoing catastrophic failure. This plastic deformation occurs due to the movement of dislocations within the material's crystal lattice structure. Characteristics of ductile materials include:

1. High tensile strength: Ductile materials typically have a high resistance to tensile stress, allowing them to withstand substantial pulling forces without fracturing.
2. Yielding behavior: Ductile materials exhibit a yielding behavior under tensile stress, where they initially deform elastically until reaching the yield point. Beyond the yield point, plastic deformation occurs, and the material undergoes permanent deformation.
3. Necking: During tensile testing, ductile materials undergo necking, where the cross-sectional area of the material decreases significantly in the region of highest stress. This localized deformation occurs just before the material reaches ultimate tensile strength.
4. Energy absorption: Ductile materials have the ability to absorb significant amounts of energy during deformation, making them suitable for applications where impact resistance is important.