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Lubricants and Surface Contact Quiz

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Questions and Answers

What causes the weed junction between two surfaces?

Interlocking of surface irregularities

Friction caused by sliding of two materials

Rolling of a load sphere or cylinder over a flat surface

Contact of asperities of both upper and lower surfaces (correct)

Which type of friction results in ploughing and interlocking of surface irregularities?

Friction caused by the contact of asperities

Sliding friction (correct)

Rolling friction

Friction caused by the sliding of two materials of different hardness

What is the relative movement of two surfaces in contact with each other called?

Contact deformation

Slide junction

Weed junction

Friction (correct)

What gets broken easily due to sliding friction?

Peaks of the softer metal (A) Signup and view all the answers

In which type of friction does a load sphere or cylinder roll over a flat surface?

Rolling friction (D) Signup and view all the answers

What is the main cause of carrying all the loads between two surfaces?

Weed junction (C) Signup and view all the answers

What is the main reason for the lower effect of rolling friction compared to sliding friction?

The coefficient of rolling friction is usually very low. (C) Signup and view all the answers

Which characteristic should a lubricant possess in order to reduce friction between two moving surfaces?

Low carbon residue (A) Signup and view all the answers

Where are solid lubricants commonly used?

For heavy machinery working at very high loads (A) Signup and view all the answers

What is the main characteristic of graphite, a widely used solid lubricant?

Has a layered structure of carbon atoms (D) Signup and view all the answers

In which type of friction is the lubricant less important according to the given information?

Rolling friction (A) Signup and view all the answers

Which type of lubricant classification includes graphite and molybdenum sulphide?

Solid lubricants (A) Signup and view all the answers

What type of bond holds the adjacent layers of carbon atoms together in graphite?

Vanderwaals force (A) Signup and view all the answers

In which condition is the coefficient of sliding friction much larger according to the text?

Static condition (C) Signup and view all the answers

What happens if the frictional heat reaches the melting temperature of the material, according to the text?

It forms a welded junction. (A) Signup and view all the answers

What should be the flash and fire points of a lubricant in comparison to the operating temperature of the machine?

Higher than the operating temperature (B) Signup and view all the answers