Tribology: Master Friction, Wear, and Lubrication for Optimal Machine Performance

Question 1

Which of the following is NOT a primary type of wear mechanism that occurs in machine components?

Accepted Answer

Corrosion

Answer

Adhesive wear

Answer

Abrasive wear

Answer

Fatigue wear

Question 2

Which wear mechanism involves surfaces sticking together and then separating, causing damage?

Accepted Answer

Adhesive wear

Answer

Abrasive wear

Answer

Erosive wear

Answer

Fretting wear

Question 3

Which of the following forces is not a type of friction encountered in machine components?

Accepted Answer

Viscous damping

Answer

Static friction

Answer

Kinetic friction

Answer

Rolling friction

Question 4

Which of the following is NOT a type of friction encountered in machine components?

Accepted Answer

Fluid drag

Answer

Coulomb friction

Answer

Viscous friction

Answer

Rolling friction

Question 5

Which of the following is an uncommon type of bearing used in machines?

Accepted Answer

Magnetic bearing

Answer

Ball bearing

Answer

Sleeve bearing

Answer

Needle bearing

Question 6

In machine design, which of the following is not a primary type of friction?

Accepted Answer

Adhesion

Answer

Coulomb friction

Answer

Viscous friction

Answer

Rolling friction

Question 7

Which of the following is not a recognized type of friction in mechanical engineering?

Accepted Answer

Magnetic friction

Answer

Static friction

Answer

Kinetic friction

Answer

Rolling friction

Question 8

In Tribology, what type of friction occurs when there is no movement between two surfaces?

Accepted Answer

Static friction

Answer

Sliding friction

Answer

Rolling friction

Answer

Coulomb friction

Question 9

Which of the following is NOT a type of wear that can occur in machine components?

Accepted Answer

Corrosion

Answer

Abrasive wear

Answer

Adhesive wear

Answer

Fatigue wear

Question 10

In tribology, which of the following is NOT a recognized type of friction encountered in machine components?

Accepted Answer

Adhesion

Answer

Sliding friction

Answer

Rolling friction

Answer

Fluid friction

Question 11

In machine components, friction can sometimes be beneficial. Which of the following is an example where friction can be advantageous?

Accepted Answer

Enhancing the grip of tires on roads, enabling vehicles to accelerate and brake effectively

Answer

Decreasing engine efficiency by converting mechanical energy into heat

Answer

Preventing the formation of oxide layers, preserving the surface integrity of components

Answer

Lowering the operating temperature of machines, extending their overall lifespan

Question 12

As per the Amontons-Coulomb law of friction, the frictional force between two surfaces is:

Accepted Answer

Proportional to the normal force between the surfaces and independent of the surface area.

Answer

Proportional to the surface area between the surfaces and independent of the normal force.

Answer

Proportional to both the normal force and the surface area between the surfaces.

Answer

Independent of both the normal force and the surface area between the surfaces.

Question 13

Which of the following is not a recognized type of friction?

Accepted Answer

Electrical friction

Answer

Sliding friction

Answer

Rolling friction

Answer

Fluid friction

Question 14

In the field of tribology, which of the following phenomena stands out as distinct from the others?

Accepted Answer

Corrosion

Answer

Adhesive wear

Answer

Fatigue wear

Answer

Abrasive wear

Question 15

What is the primary purpose of lubrication in machine components?

Accepted Answer

Minimize friction and wear

Answer

Increase friction and wear

Answer

Prevent corrosion

Answer

Generate heat

Question 16

In a hydrodynamic journal bearing, which mechanism is essential for separating the shaft from the bearing surface and creating a lubricating film?

Accepted Answer

Hydrodynamic lubrication

Answer

Coulomb friction

Answer

Boundary lubrication

Answer

Rolling friction

Question 17

Which of the following is NOT a fundamental wear mechanism?

Accepted Answer

Electrical wear

Answer

Adhesive wear

Answer

Abrasive wear

Answer

Surface fatigue

Question 18

Which of the following is not a type of tribometer used to measure friction and wear?

Accepted Answer

Scanning probe microscope

Answer

Pin-on-disk

Answer

Ball-on-flat

Answer

Four-ball

Question 19

Which statement accurately describes friction?

Accepted Answer

Friction results from the interaction of surface irregularities.

Answer

Friction is always a negative force.

Answer

Friction is not affected by the contact area between two surfaces.

Answer

Friction always leads to wear.

Question 20

In tribology, which technique involves direct sliding contact to assess material wear properties?

Accepted Answer

Pin-on-disk tribometer

Answer

Atomic force microscopy (AFM)

Answer

Scanning electron microscopy (SEM)

Answer

X-ray diffraction (XRD)

Question 21

Which tribological testing method is specifically designed to assess the wear resistance of materials under controlled loading and sliding conditions?

Accepted Answer

Pin-on-disk test

Answer

Scanning Electron Microscopy (SEM)

Answer

Atomic Force Microscopy (AFM)

Answer

X-ray Diffraction (XRD)

Question 22

Which of the following describes adhesive wear?

Accepted Answer

Two surfaces in contact stick together and tear apart during sliding.

Answer

Repeated plastic deformation occurs on one surface, removing material.

Answer

Cracks form and grow beneath the surface due to repeated loading and unloading.

Answer

Surface material melts and re-solidifies due to excessive heat generated during sliding.

Question 23

Which technique is **not** commonly employed in tribology to analyze the failure surfaces of components?

Accepted Answer

Fourier Transform Infrared Spectroscopy (FTIR)

Answer

Scanning Electron Microscopy (SEM)

Answer

Energy-Dispersive X-ray Spectroscopy (EDS)

Question 24

Which type of friction is NOT a solid friction?

Accepted Answer

Fluid friction

Answer

Static friction

Answer

Rolling friction

Answer

Dynamic friction

Question 25

Which tribological testing method is designed to evaluate friction coefficients under varying speeds and loads?

Accepted Answer

Pin-on-disk test

Answer

Scratch test

Answer

Ball-on-flat test

Question 26

Which of the following is not a recognized type of friction?

Accepted Answer

Electrical friction

Answer

Static friction

Answer

Kinetic friction

Answer

Rolling friction

Question 27

In the context of lubrication, which of the following factors is NOT directly affected by the properties of the lubricant?

Accepted Answer

Temperature

Answer

Film thickness

Answer

Friction coefficient

Answer

Wear rate

Question 28

Which of the following is NOT a type of wear mechanism?

Accepted Answer

Oxidation

Answer

Adhesive wear

Answer

Abrasive wear

Answer

Fatigue wear

Question 29

Which of the following accurately describes the nature of friction?

Accepted Answer

Friction hinders the relative motion of contacting surfaces.

Answer

Friction always aligns with the applied force.

Answer

Friction remains unaffected by surface roughness.

Answer

Friction is always advantageous in machine components.

Question 30

In tribology, which method is used to evaluate lubricant effectiveness in reducing friction and wear under controlled conditions?

Accepted Answer

Pin-on-disk test

Answer

Scanning electron microscopy

Answer

X-ray diffraction

Answer

Atomic force microscopy

Question 31

In a journal bearing system, which design factor is most critical for ensuring adequate lubrication?

Accepted Answer

Radial clearance

Answer

Shaft speed

Answer

Bearing material

Answer

Applied load

Question 32

How does the Stribeck curve help us understand different lubrication regimes?

Accepted Answer

It shows the transition points between boundary, mixed, and hydrodynamic lubrication based on operating conditions.

Answer

It calculates the frictional force between contacting surfaces.

Answer

It predicts the wear rate of lubricated components.

Question 33

Which factors significantly influence the coefficient of friction between two contacting surfaces?

Accepted Answer

Surface roughness, temperature, load, and lubrication

Answer

Surface color and humidity

Answer

The coefficient of friction is constant for any material pair.

Answer

The coefficient of friction depends solely on the type of lubrication used.

Question 34

How does lubricant rheology influence the design of lubrication systems?

Accepted Answer

It determines pressure distribution in the lubricant film, affecting load-bearing capacity and friction reduction.

Answer

It is only crucial for high-speed applications with hydrodynamic lubrication.

Answer

It has no direct impact on the wear rate of contacting surfaces.

Question 35

How does surface topography influence the performance of hydrodynamic bearings?

Accepted Answer

Surface topography affects lubricant film thickness, pressure distribution, and load-carrying capacity.

Answer

Surface topography has no impact on bearing performance.

Answer

Surface topography affects lubricant film thickness only.

Answer

Surface topography affects pressure distribution only.

Question 36

How do surface engineering techniques enhance the tribological performance of materials?

Accepted Answer

By modifying surface properties like roughness, chemical composition, and crystal structure

Answer

By increasing surface thickness and hardness

Answer

By solely improving wear resistance

Answer

By being applicable only to metallic materials

Question 37

When choosing materials for tribological components that face high contact stresses, which property is crucial to consider?

Accepted Answer

Material hardness

Answer

Material toughness

Answer

Material density

Answer

Material electrical conductivity

Question 38

An automotive engineer aims to enhance the fuel efficiency of a new vehicle model. Which case study is most applicable to guide their tribological design choices?

Accepted Answer

Tribological investigation of friction and wear in automotive engines

Answer

Tribological analysis of wind turbine bearings

Answer

Tribological optimization of a high-speed machine spindle

Answer

Tribological characterization of biomaterials for medical implants

Question 39

In the field of tribology, what ethical considerations should engineers prioritize to ensure responsible resource use and minimize environmental impact?

Accepted Answer

Engineers should prioritize sustainable materials and practices to minimize tribology's environmental impact.

Answer

Ethical considerations are not relevant in tribology.

Answer

Engineers have no responsibility for the environmental impact of their tribological designs.

Answer

Responsible resource use in tribology focuses solely on reducing lubricant costs.

Question 40

Which wear mechanism involves the embedding of hard particles into a softer surface?

Accepted Answer

Abrasive wear

Answer

Adhesive wear

Answer

Erosive wear

Answer

Fretting wear

Question 41

What is the Hertzian contact stress equation commonly used for?

Accepted Answer

Calculating the maximum contact stress between two elastic bodies

Answer

Predicting the wear rate of a bearing

Answer

Determining the coefficient of friction in boundary lubrication

Answer

Analyzing the lubrication film thickness in hydrodynamic lubrication

Question 42

Which of the following lubrication regimes typically operates at the lowest coefficient of friction?

Accepted Answer

Hydrodynamic lubrication

Answer

Boundary lubrication

Answer

Mixed lubrication

Answer

Elastohydrodynamic lubrication

Question 43

What is the primary goal of tribology in mechanical engineering?

Accepted Answer

To minimize friction, wear, and temperature in machine components

Answer

To increase the efficiency of power transmission systems

Answer

To improve the lifespan of mechanical equipment

Answer

To reduce noise and vibration in machinery

Question 44

Which of the following statements about the Stribeck curve is correct?

Accepted Answer

It describes the relationship between friction and lubrication regime.

Answer

It can be used to predict the lifespan of a bearing.

Answer

It is independent of the operating conditions of a tribological system.

Answer

It only applies to hydrodynamic lubrication.

Question 45

In tribology, which statement best describes the Hertzian contact theory?

Accepted Answer

Analyzes elastic deformation of loaded contacting surfaces

Answer

Applicable only to static contact situations

Answer

Assumes perfectly flat contacting surfaces

Answer

Unsuitable for analyzing lubricated contacts

Question 46

Which lubrication type entails the complete separation of two solid surfaces by a lubricating film, eliminating direct contact and minimizing friction and wear?

Accepted Answer

Hydrodynamic lubrication

Answer

Boundary lubrication

Answer

Mixed lubrication

Answer

Elastohydrodynamic lubrication

Question 47

Identify the type of friction that occurs when two surfaces are not in relative motion.

Accepted Answer

Static friction

Answer

Rolling friction

Answer

Boundary friction

Answer

Kinetic friction

Question 48

Define wear as it pertains to tribology.

Accepted Answer

The gradual removal of material from a surface due to friction

Answer

The accumulation of material on a surface due to wear particles

Answer

The deformation of a surface due to contact stress

Answer

The change in surface roughness over time

Question 49

Hydrodynamic lubrication occurs when:

Accepted Answer

A thin film of lubricant separates the contacting surfaces

Answer

The surfaces are in direct contact

Answer

The lubricant is in a solid state

Answer

The surfaces are lubricated by a boundary layer of lubricant

Question 50

Which factor does NOT influence the coefficient of friction?

Accepted Answer

Fluid viscosity

Answer

Surface roughness

Answer

Normal load

Answer

Temperature

Question 51

Which type of lubrication provides the highest load-bearing capacity in tribological systems?

Accepted Answer

Elastohydrodynamic lubrication

Answer

Hydrodynamic lubrication

Answer

Boundary lubrication

Answer

Mixed lubrication

Question 52

The Stribeck curve primarily relates the coefficient of friction to:

Accepted Answer

Speed

Answer

Viscosity

Answer

Load

Answer

Temperature

Question 53

The Hertzian contact theory is primarily used to analyze:

Accepted Answer

Contact stresses in elastic bodies

Answer

Wear mechanisms in sliding contacts

Answer

Fluid flow in lubrication systems

Answer

Friction coefficients in dry contacts

Question 54

Which property is crucial for a material used as a bearing liner in tribological applications?

Accepted Answer

Low wear rate

Answer

Low friction coefficient

Answer

High hardness

Answer

High thermal conductivity

Question 55

What is the term for the combined effect of friction and corrosion on materials?

Accepted Answer

Tribocorrosion

Answer

Lubrication-induced corrosion

Answer

Friction-reducing corrosion

Question 56

Define mixed lubrication and explain its significance in tribological systems.

Accepted Answer

Mixed lubrication occurs when both boundary and hydrodynamic lubrication mechanisms coexist in a tribological contact.

Answer

Mixed lubrication typically results in higher friction and wear compared to pure hydrodynamic or boundary lubrication.

Answer

Mixed lubrication is rarely encountered in practical engineering applications.

Question 57

In lubricated contacts, why does the coefficient of friction decrease as boundary layers form?

Accepted Answer

Boundary layers minimize direct contact between surfaces.

Answer

Boundary layers increase surface roughness.

Answer

Boundary layers enhance surface elasticity.

Answer

Boundary layers elevate contact temperature.

Question 58

Identify the option below that is NOT considered a prevalent wear mechanism:

Accepted Answer

Creeping wear

Answer

Adhesive wear

Answer

Abrasive wear

Answer

Fatigue wear

Question 59

What is the principal function of a lubricant?

Accepted Answer

Reduce friction and wear between surfaces

Answer

Dissipate heat generated by friction

Answer

Prevent corrosion

Answer

Enhance the aesthetics of machine components

Question 60

Which of the following is NOT a type of boundary lubrication?

Accepted Answer

Lubricant film separation

Answer

Gibbs adsorption layer formation

Answer

Physical adsorption

Answer

Chemical bonding

Question 61

What is the primary mechanism responsible for friction in hydrodynamic lubrication?

Accepted Answer

Fluid viscosity

Answer

Solid-to-solid contact

Answer

Adhesion

Answer

Elastic deformation

Question 62

Explain tribochemistry and describe its impact on the characteristics of surfaces in tribological systems.

Accepted Answer

Tribochemistry involves chemical reactions at contact surfaces, affecting wear debris formation and altering surface properties.

Answer

Tribochemistry focuses only on the lubrication effects of lubricants in reducing friction.

Answer

Tribochemistry has a negligible impact on the performance of tribological systems.

Question 63

In rolling contacts, which mechanism is primarily responsible for wear?

Accepted Answer

Fatigue

Answer

Corrosion

Answer

Adhesion

Answer

Abrasion

Question 64

Which type of lubrication ensures a complete separating film between contacting surfaces?

Accepted Answer

Hydrodynamic lubrication

Answer

Boundary lubrication

Answer

Elastohydrodynamic lubrication

Answer

Mixed lubrication