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Unit 3: Stress and strain - Practice Quiz

BTY730 — Biomechanics 60 Questions
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1 Which of the following is the correct definition of stress?

stress and strain Easy
A. Force applied per unit area
B. Force multiplied by area
C. Change in length per unit length
D. Length divided by force

2 Strain is best described as which of the following?

stress and strain Easy
A. Force per unit area of a body
B. Total force acting on a body
C. Product of stress and area
D. Ratio of change in length to original length

3 What is the SI unit of stress?

stress and strain Easy
A. Pascal ()
B. Meter ()
C. Joule ()
D. Newton ()

4 What is the unit of strain?

stress and strain Easy
A. Dimensionless (no unit)
B. Pascal ()
C. Newton ()
D. Meter ()

5 Hooke's law states that within the elastic limit, stress is:

Hooke's law Easy
A. Independent of strain
B. Inversely proportional to strain
C. Directly proportional to strain
D. Equal to the square of strain

6 The constant of proportionality in Hooke's law is known as:

Hooke's law Easy
A. Yield stress
B. Young's modulus
C. Poisson's ratio
D. Shear strain

7 When a force is applied to a body causing it to change shape or size, this change is called:

applied forces and deformations Easy
A. Deformation
B. Momentum
C. Density
D. Acceleration

8 A force that tends to stretch or elongate a material is called:

basic loading configurations Easy
A. Shear force
B. Tensile force
C. Compressive force
D. Torsional force

9 A force that tends to shorten or squeeze a material is known as:

basic loading configurations Easy
A. Compressive force
B. Tensile force
C. Bending force
D. Shear force

10 Forces acting parallel to a surface, causing layers to slide past one another, produce:

basic loading configurations Easy
A. Compressive stress
B. Tensile stress
C. Shear stress
D. Normal stress

11 In a uniaxial tension test, the load is applied in how many directions along the specimen?

uniaxial tension test Easy
A. Three directions simultaneously
B. One direction (along a single axis)
C. Two perpendicular directions
D. In a circular pattern

12 What is typically measured during a uniaxial tension test?

uniaxial tension test Easy
A. Density and volume
B. Color and texture
C. Temperature and pressure
D. Load and elongation of the specimen

13 A load-elongation diagram plots load against which quantity?

load-elongation diagrams Easy
A. Cross-sectional area
B. Temperature
C. Elongation (change in length)
D. Time only

14 The initial straight-line portion of a load-elongation diagram represents which type of behavior?

load-elongation diagrams Easy
A. Fracture behavior
B. Linear elastic behavior
C. Plastic behavior
D. Necking behavior

15 The maximum stress a material can withstand before fracture, as read from a stress-strain diagram, is called:

properties based on stress-strain diagrams Easy
A. Ultimate tensile strength
B. Yield point
C. Elastic modulus
D. Proportional limit

16 The stress at which a material begins to deform permanently is called the:

properties based on stress-strain diagrams Easy
A. Yield stress
B. Poisson's ratio
C. Fracture strain
D. Ultimate stress

17 A material's ability to undergo large plastic deformation before fracture is called:

properties based on stress-strain diagrams Easy
A. Brittleness
B. Elasticity
C. Ductility
D. Hardness

18 A material that fractures with little or no plastic deformation is described as:

mechanical properties of materials Easy
A. Tough
B. Ductile
C. Elastic
D. Brittle

19 Which mechanical property describes a material's stiffness or resistance to elastic deformation?

mechanical properties of materials Easy
A. Modulus of elasticity
B. Hardness
C. Ductility
D. Toughness

20 An idealized material that returns to its original shape completely after the load is removed is called:

idealized model for material behavior Easy
A. Perfectly plastic
B. Perfectly elastic
C. Viscous
D. Rigid-brittle

21 A cylindrical bone specimen with a cross-sectional area of is subjected to an axial load of . What is the normal stress developed in the specimen?

stress and strain Medium
A.
B.
C.
D.

22 A tendon of original length elongates by under load. What is the engineering strain?

stress and strain Medium
A.
B.
C.
D.

23 A material in the linear elastic region has a Young's modulus of . If the applied stress is , what is the resulting strain?

Hooke's law Medium
A.
B.
C.
D.

24 The area under the entire stress-strain curve up to fracture represents which mechanical property?

properties based on stress-strain diagrams Medium
A. Toughness (energy absorbed per unit volume)
B. Yield strength of the material
C. Stiffness of the material
D. Elastic resilience only

25 Two materials A and B are tested. A shows a steeper initial slope in its stress-strain diagram than B. Which statement is correct?

properties based on stress-strain diagrams Medium
A. Material A has a lower stiffness than B
B. Material A is more ductile than B
C. Material A has a higher elastic modulus than B
D. Material A has a higher fracture strain than B

26 In a uniaxial tension test, the extensometer measures gauge length change while the load cell measures force. What is the primary purpose of using a defined gauge length?

uniaxial tension test Medium
A. To reduce the cross-sectional area
B. To compute strain over a uniform deformation region
C. To eliminate the elastic region
D. To increase the applied load capacity

27 A load-elongation diagram differs from a stress-strain diagram primarily because it depends on:

load-elongation diagrams Medium
A. The strain rate exclusively
B. The temperature of testing alone
C. Only the material's elastic modulus
D. The specimen geometry (area and length)

28 A rivet connecting two overlapping plates carries a transverse force tending to slide the plates past one another. This rivet is primarily subjected to which type of loading?

basic loading configurations Medium
A. Shear
B. Axial tension
C. Torsion
D. Pure bending

29 A material has a yield strength of and an ultimate tensile strength of . During loading the stress reaches . What is the expected behavior?

mechanical properties of materials Medium
A. The material behaves purely elastically
B. Permanent (plastic) deformation occurs
C. No deformation occurs at all
D. The material has fractured

30 In an idealized elastic-perfectly plastic model, what happens to stress once the yield point is reached?

idealized model for material behavior Medium
A. Stress remains constant while strain increases
B. Stress increases linearly with strain
C. Stress increases exponentially
D. Stress drops immediately to zero

31 A steel wire () of length and cross-sectional area carries a load of . What is the elongation?

Hooke's law Medium
A.
B.
C.
D.

32 When an axial tensile force stretches a rod, the rod's diameter typically decreases. The ratio of lateral strain to axial strain is known as:

applied forces and deformations Medium
A. Bulk modulus
B. Young's modulus
C. Shear modulus
D. Poisson's ratio

33 The area under the stress-strain curve up to the elastic limit represents which property?

properties based on stress-strain diagrams Medium
A. Modulus of toughness
B. Modulus of resilience
C. Ultimate strength
D. Ductility

34 During a uniaxial tension test on a ductile metal, localized reduction in cross-sectional area just before fracture is called:

uniaxial tension test Medium
A. Buckling
B. Necking
C. Yielding
D. Creep

35 On a load-elongation diagram of a ductile material, the peak load corresponds to which point on the corresponding stress-strain curve?

load-elongation diagrams Medium
A. Elastic limit
B. Fracture point
C. Ultimate tensile strength
D. Proportional limit

36 Material X fractures at a strain of while material Y fractures at a strain of . Which conclusion is correct?

mechanical properties of materials Medium
A. Both have identical ductility
B. Material X is more ductile than Y
C. Material Y is more ductile than X
D. Material X is tougher by definition

37 A rod carries a fixed axial load. If its diameter is doubled, how does the normal stress change?

stress and strain Medium
A. It decreases to one-half
B. It decreases to one-fourth
C. It doubles
D. It remains unchanged

38 A long slender column under axial compression tends to fail by lateral bending rather than crushing. This failure mode is called:

basic loading configurations Medium
A. Buckling
B. Tensile rupture
C. Torsional fracture
D. Shear failure

39 A rigid-plastic idealized model neglects which behavior compared to real materials?

idealized model for material behavior Medium
A. Fracture at large strains
B. Plastic flow after yielding
C. Constant yield stress
D. Elastic deformation before yielding

40 Two rods of the same material and length carry the same load, but rod P has twice the cross-sectional area of rod Q. How does the elongation of P compare to Q?

applied forces and deformations Medium
A. P elongates four times as much as Q
B. P elongates half as much as Q
C. P elongates twice as much as Q
D. P and Q elongate equally

41 A cylindrical bone specimen of initial diameter carries an axial tensile load of . If the material is assumed incompressible () and the axial engineering strain is , what is the approximate true stress at this load?

stress and strain Hard
A.
B.
C.
D.

42 A tendon behaves linearly with up to a strain of . If a specimen of length and cross-section is stretched to within the elastic range, what force is required?

Hooke's law Hard
A.
B.
C.
D.

43 Two materials A and B have identical yield strengths but material A has twice the area under its full stress-strain curve. Which statement is most accurate?

properties based on stress-strain diagrams Hard
A. A and B have identical toughness and resilience
B. A is tougher than B but they may have equal resilience
C. A has higher resilience but equal toughness
D. A is more brittle than B with higher stiffness

44 During a uniaxial tension test, necking begins. Which condition marks the onset of necking (instability) in terms of true stress and true strain ?

uniaxial tension test Hard
A.
B.
C.
D.

45 A load-elongation curve is converted to a stress-strain curve. Two identical materials tested as bars of different lengths and cross-sections will produce load-elongation curves that:

load-elongation diagrams Hard
A. Cannot be compared without knowing the modulus
B. Are identical regardless of geometry
C. Yield different stress-strain curves due to geometry
D. Differ in shape but yield identical stress-strain curves

46 A material has and yield strength . What is its modulus of resilience?

mechanical properties of materials Hard
A.
B.
C.
D.

47 A stepped bar has segment 1 (, ) and segment 2 (, ), same material , under axial load . What is the total elongation?

applied forces and deformations Hard
A.
B.
C.
D.

48 In an elastic-perfectly plastic idealized model, once the yield stress is reached, the material:

idealized model for material behavior Hard
A. Deforms at constant stress with no strain hardening
B. Continues to harden linearly
C. Fractures immediately
D. Recovers elastically upon further loading

49 A thin-walled pressure vessel of radius and wall thickness () is under internal pressure . The ratio of hoop stress to longitudinal stress is:

basic loading configurations Hard
A.
B.
C.
D.

50 A material under biaxial stress has , , , . What is the strain in the -direction ?

stress and strain Hard
A.
B.
C.
D.

51 For a material displaying no distinct yield point, the yield strength is commonly determined using the:

properties based on stress-strain diagrams Hard
A. offset method on the stress-strain curve
B. Intersection with the elastic modulus line at origin
C. Peak of the load-elongation curve
D. Point of fracture on the true stress curve

52 In a tension test, the engineering stress at fracture is lower than ultimate tensile strength, yet the true stress at fracture is highest. This is because:

uniaxial tension test Hard
A. The gauge length increases faster than area decreases
B. Engineering stress uses instantaneous area
C. The material becomes stronger after UTS
D. Necking reduces actual area while load drops less proportionally

53 A composite rod consists of a steel core (, ) bonded to an aluminum sleeve (, ) under axial load with equal strain. What fraction of the total load does the steel carry?

Hooke's law Hard
A.
B.
C.
D.

54 Material X: high strength, low ductility, small elongation at fracture. Material Y: moderate strength, high ductility. Which is more suitable for an application requiring energy absorption before failure?

mechanical properties of materials Hard
A. Material Y, due to greater toughness from ductility
B. Material X, due to higher strength
C. Both equally, since strength governs energy
D. Material X, because strength dominates toughness

55 A tapered bar of length has diameter varying linearly from to under axial load and modulus . Its elongation is:

applied forces and deformations Hard
A.
B.
C.
D.

56 A bilinear (elastic-linear hardening) model has elastic modulus up to yield strain , then tangent modulus . What is the stress at total strain ?

idealized model for material behavior Hard
A.
B.
C.
D.

57 A bar is subjected to combined axial load and its own weight (density , length , area , load at bottom). The maximum normal stress occurs at the:

basic loading configurations Hard
A. Top of the bar, equal to
B. Midpoint, equal to
C. Top of the bar, equal to
D. Bottom of the bar, equal to

58 A rectangular block () undergoes an axial strain of with . What is the approximate change in volume ratio ?

stress and strain Hard
A.
B.
C.
D.

59 Two specimens of the same material but with gauge lengths and are tested. Regarding percent elongation at fracture, which is true?

load-elongation diagrams Hard
A. The longer gauge length reports higher percent elongation
B. Both report identical percent elongation
C. The shorter gauge length usually reports higher percent elongation
D. Percent elongation is independent of gauge length

60 A specimen with original area shows area at fracture. What is its percent reduction in area, and what does it indicate?

uniaxial tension test Hard
A. , a measure of resilience
B. , a measure of toughness
C. , a measure of ductility
D. , a measure of stiffness
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