TRIBOLOGY EXAM QUESTIONS VERIFIED
ANSWERS
What is tribology? - ANSWER Science and engineering of rubbing surfaces
Includes study and application of friction, wear and lubrication
Friction? - ANSWER force resisting relative motion of solid surfaces, fluid
layers, and material elements sliding against each other
Two forms of friction? - ANSWER static and kinetic friction
Static friction? - ANSWER when 2 objects are not moving relative to each
other
Kinetic friction? - ANSWER when 2 objects are moving relative to each other
Wear? - ANSWER Loss of material from surface or displacement of material
from its original position on solid surface performed by action of another
surface
Lubrication? - ANSWER Process of reducing friction b/w and wear on one or
both surfaces in proximity and moving relative to each other by interposing a
substance called a lubricant in b/w them
3 laws of friction? - ANSWER 1.) force of friction is directly proportional to
applied load (normal force)
2.) Force of friction is independent of apparent area of contact
3.) Kinetic friction is independent of sliding velocity--> means that friction used
to initiate sliding is same as friction seen to initiate sliding
When 2 surfaces are in contact, what is the real area of contact a collection of? -
ANSWER collection of microscopic contacts (real area of contact) that are
distributed across the apparent area of contact
Friction coefficient? - ANSWER ratio of friction force to normal force
, Wear rate? - ANSWER volume lost per unit normal load per distance of
sliding)
Surfaces have roughness and these peaks are called what? - ANSWER
Asperities
Friction in dentistry? 2 simple examples of Pro-friction? - ANSWER - Hand
instruments
- Removalable partial denture
What holds removable partial denture in place? - ANSWER Undercut and
friction that hold RPD in place
Protraction
Instances of anti-friction? - ANSWER Braces
- claims that self-ligating brackets exert lower ligation force, frictional
resistance is minimized, leading to less unwanted forces in magnitude and
direction
Types of wear? - ANSWER - Adhesive
- Abrasive (2-body and 3-body)
- Corrosive
- Fatigue
- Other types of wear
What is adhesive wear? - ANSWER When 2 smooth bodies are slide over each
other and fragment is pulled off one surface and adheres to another
Later, fragment may be pulled off the surface and returned to original surface or
to form loose wear particles
What does adhesive wear arise from? - ANSWER from strong adhesive forces
that arise when atoms come into intimate contact under pressure
In adhesive wear, where does bonding occur? - ANSWER at contact b/w two
surfaces that are then separated
ANSWERS
What is tribology? - ANSWER Science and engineering of rubbing surfaces
Includes study and application of friction, wear and lubrication
Friction? - ANSWER force resisting relative motion of solid surfaces, fluid
layers, and material elements sliding against each other
Two forms of friction? - ANSWER static and kinetic friction
Static friction? - ANSWER when 2 objects are not moving relative to each
other
Kinetic friction? - ANSWER when 2 objects are moving relative to each other
Wear? - ANSWER Loss of material from surface or displacement of material
from its original position on solid surface performed by action of another
surface
Lubrication? - ANSWER Process of reducing friction b/w and wear on one or
both surfaces in proximity and moving relative to each other by interposing a
substance called a lubricant in b/w them
3 laws of friction? - ANSWER 1.) force of friction is directly proportional to
applied load (normal force)
2.) Force of friction is independent of apparent area of contact
3.) Kinetic friction is independent of sliding velocity--> means that friction used
to initiate sliding is same as friction seen to initiate sliding
When 2 surfaces are in contact, what is the real area of contact a collection of? -
ANSWER collection of microscopic contacts (real area of contact) that are
distributed across the apparent area of contact
Friction coefficient? - ANSWER ratio of friction force to normal force
, Wear rate? - ANSWER volume lost per unit normal load per distance of
sliding)
Surfaces have roughness and these peaks are called what? - ANSWER
Asperities
Friction in dentistry? 2 simple examples of Pro-friction? - ANSWER - Hand
instruments
- Removalable partial denture
What holds removable partial denture in place? - ANSWER Undercut and
friction that hold RPD in place
Protraction
Instances of anti-friction? - ANSWER Braces
- claims that self-ligating brackets exert lower ligation force, frictional
resistance is minimized, leading to less unwanted forces in magnitude and
direction
Types of wear? - ANSWER - Adhesive
- Abrasive (2-body and 3-body)
- Corrosive
- Fatigue
- Other types of wear
What is adhesive wear? - ANSWER When 2 smooth bodies are slide over each
other and fragment is pulled off one surface and adheres to another
Later, fragment may be pulled off the surface and returned to original surface or
to form loose wear particles
What does adhesive wear arise from? - ANSWER from strong adhesive forces
that arise when atoms come into intimate contact under pressure
In adhesive wear, where does bonding occur? - ANSWER at contact b/w two
surfaces that are then separated
