Which components contributes the average surface roughness?*a) Waviness and roughnessb) Lay, Flawc) Only ad) All the above

The components that contribute to the average surface roughness are both waviness and roughness. Therefore, the answer is a) Waviness and roughness.

Here's why:

1. Waviness: This is the broader, larger-scale component of surface texture. It's caused by factors such as machine or tool vibrations, warping, or heat treatment. Waviness can significantly affect the contact area between two surfaces, which in turn can influence friction, wear, and lubrication.

2. Roughness: This is the finer, smaller-scale component of surface texture. It's caused by the cutting action of the tool that shapes the surface. Roughness can affect various properties of the surface, such as its ability to retain lubricant, its friction characteristics, and its appearance.

Lay and flaw are also aspects of surface texture, but they are not directly related to the average surface roughness. Lay refers to the direction of the predominant surface pattern, usually determined by the last machining process. Flaws are irregularities or defects on the surface. While these can affect the performance of the surface, they are not part of the calculation of average surface roughness.