Mechanical Properties of Matter

Question 1

Mechanical Properties

Answer 1

Changes in material that result when force is applied

Question 2

Stress

Answer 2

Tendency to change the position of rest or motion of a mass

Question 3

Strain

Answer 3

Deformation occurs if the position or motion of the mass cannot be changed

Question 4

What are the 3 types of stresses?

Answer 4

tensile, compression, shear

Question 5

Elastic Strain

Answer 5

Reversible strain

Question 6

What is Hooks Law?

Answer 6

Elastic Strain which is reversible type of strain

Non-permanent deformation (ex:spring)

Question 7

Plastic strain

Answer 7

Permanent deformation

Question 8

Elastic modulus = Young Modulus

Answer 8

Slope of the stress/strain curve indicates rigidity or stiffness
(only within the elastic range)

Question 9

Elastic Limit = Proportional Limit = Yield Strength

Answer 9

Where permanent deformation begins

Question 10

Ultimate strength

Answer 10

Point of actual fracture

Question 11

Resilience

Answer 11

Energy needed to deform a material to its elastic limit; resistance to permanent deformation;
area under elastic portion of stress-stain curve

Question 12

Toughness

Answer 12

Energy needed for fracture; area under elastic an plastic portions of stress/strain curve

Question 13

Hardness

Answer 13

Resistance to indentation and scratching

Question 14

How is hardness tested?

Answer 14

Hardness is tested by the diameter of depression based on the stylus and force used (Brinell, Knoop, Vickers #’s)

Question 15

Rheology

Answer 15

Flowability = relative viscosity

Question 16

Abrasion Resistance

Answer 16

Can be experimentally tested with toothbrush abrasion lab machines to stimulate oral conditions.
May involve factors of resilience and toughness.
Wear is often related to surface hardness