What effect does an increase in surface roughness have on friction?

An increase in surface roughness generally leads to an increase in friction. This is due to the fact that rougher surfaces create more interlocking points and greater contact area between the surfaces in contact. As the microscopic peaks and valleys of the surfaces interact, they can create additional resistance to motion, which in turn increases the frictional force.

Additionally, rough surfaces tend to form larger and more complex contact patches compared to smooth surfaces. This complexity can contribute to a higher coefficient of friction because it provides more surface area for adhesion and mechanical interlocking.

In essence, when the surfaces are roughened, the mechanical interactions increase, which results in a heightened level of friction encountered when attempting to slide one surface over another. This principle is critical in various engineering applications, where controlling friction is essential for safe and efficient operation.