When two surfaces are coated with a lubricant, then they:
A
Stick to each other
B
Slide upon each other
C
Roll upon each other
D
None of these
Step-by-Step Solution
Function of Lubricants: Lubricants (like oil or grease) are applied between two surfaces to reduce friction. They fill the minute irregularities (depressions and elevations) on the surfaces.
Mechanism: The lubricant forms a thin layer separating the two solid surfaces. Consequently, the actual contact between the solid surfaces is replaced by the contact between liquid layers of the lubricant.
Result: Since the fluid friction (viscosity) is generally much lower than the dry sliding friction between solids, the surfaces move smoothly relative to one another. This relative motion is a 'sliding' motion, unlike ball bearings which convert sliding friction into rolling friction [Source 69].
Practice Mode Available
Master this Topic on Sushrut
Join thousands of students and practice with AI-generated mock tests.