Physics Test On Modulus Of Elasticity! Trivia Quiz

1. The angle of the principle direction of stress for a torsion specimen is 45 degrees to the specimens longitudinal axis.

True

False

The angle of the principal direction of stress for a torsion specimen being 45 degrees to the specimen's longitudinal axis means that the maximum shear stress occurs at a 45-degree angle to the longitudinal axis. This is true because in torsion, the shear stress is maximum at a 45-degree angle to the axis of the shaft.

Explanation

The angle of the principal direction of stress for a torsion specimen being 45 degrees to the specimen's longitudinal axis means that the maximum shear stress occurs at a 45-degree angle to the longitudinal axis. This is true because in torsion, the shear stress is maximum at a 45-degree angle to the axis of the shaft.

2. Aluminum is a material with ductile behavior.

True

False

Aluminum is a material with ductile behavior because it can be easily stretched or bent without breaking. Ductility is a property of materials that allows them to be deformed under tensile stress, and aluminum is known for its high ductility. This property makes aluminum suitable for various applications, such as in construction, automotive, and aerospace industries, where materials need to withstand deformation without fracturing.

Explanation

Aluminum is a material with ductile behavior because it can be easily stretched or bent without breaking. Ductility is a property of materials that allows them to be deformed under tensile stress, and aluminum is known for its high ductility. This property makes aluminum suitable for various applications, such as in construction, automotive, and aerospace industries, where materials need to withstand deformation without fracturing.

3. No permanent deformation happens in the elastic region in tension.

True

False

In the elastic region, materials can be stretched or compressed without causing any permanent deformation. This means that once the applied force is removed, the material will return to its original shape and size. Therefore, it is true that no permanent deformation occurs in the elastic region in tension.

Explanation

In the elastic region, materials can be stretched or compressed without causing any permanent deformation. This means that once the applied force is removed, the material will return to its original shape and size. Therefore, it is true that no permanent deformation occurs in the elastic region in tension.

4. Materials that fail catastrophically in the elastic region (of a tensile test) are known as brittle.

True

False

Materials that fail catastrophically in the elastic region of a tensile test are known as brittle. This means that when these materials are subjected to stress, they do not exhibit significant plastic deformation and instead fracture suddenly and without warning. This behavior is characteristic of brittle materials such as glass or cast iron, which do not have the ability to absorb energy and deform plastically before breaking.

Explanation

Materials that fail catastrophically in the elastic region of a tensile test are known as brittle. This means that when these materials are subjected to stress, they do not exhibit significant plastic deformation and instead fracture suddenly and without warning. This behavior is characteristic of brittle materials such as glass or cast iron, which do not have the ability to absorb energy and deform plastically before breaking.

5. Is [your statement here] true or false?

True

False

The given correct answer is true because it directly states that the statement is indeed true.

Explanation

The given correct answer is true because it directly states that the statement is indeed true.

6. Photoelasticity can be applied to any isotropic, homogeneous material within the elastic region.

True

False

no material constants in the equation

Explanation

no material constants in the equation

7. A specimen with a notch in tension has a Kt values of 4.25. The specimen is sensitive to the presence of the notch.

True

False

Kt values of about 1 are insensitive

Explanation

Kt values of about 1 are insensitive

8. Rockwell Hardness requires a correction for curvature if performed on curved surfaces.

True

False

Rockwell Hardness is a measure of a material's resistance to indentation. When performing the test on curved surfaces, the curvature can affect the accuracy of the measurement. The curvature can cause uneven distribution of the applied force, leading to inconsistent results. Therefore, a correction is necessary to account for the curvature and obtain accurate Rockwell Hardness readings on curved surfaces.

Explanation

Rockwell Hardness is a measure of a material's resistance to indentation. When performing the test on curved surfaces, the curvature can affect the accuracy of the measurement. The curvature can cause uneven distribution of the applied force, leading to inconsistent results. Therefore, a correction is necessary to account for the curvature and obtain accurate Rockwell Hardness readings on curved surfaces.

9. Brinell testing is the largest of the indentors.

True

False

10 mm diameter

Explanation

10 mm diameter

10. The elastic modulus relates stress to strain by Hooke's Law.

True

False

For linear materials

Explanation

For linear materials

11. There is zero shear stress between the two inner rollers for four point bending.

True

False

Constant moment area means zero stress

Explanation

Constant moment area means zero stress

12. When there is both an upper and lower yield point for a material, the lower point should be used.

True

False

The upper point is unstable.

Explanation

The upper point is unstable.

13. The elastic region has a uniform stress state in tension.

True

False

In the elastic region, when a material is subjected to tension, the stress state is uniform. This means that the stress is evenly distributed throughout the material, resulting in a uniform deformation. This is because the material is still within its elastic limit, where it can deform reversibly and return to its original shape once the load is removed. Therefore, the given statement is true.

Explanation

In the elastic region, when a material is subjected to tension, the stress state is uniform. This means that the stress is evenly distributed throughout the material, resulting in a uniform deformation. This is because the material is still within its elastic limit, where it can deform reversibly and return to its original shape once the load is removed. Therefore, the given statement is true.

14. There is permanent damage in the plastic region for tension

True

False

In the plastic region, the material undergoes permanent deformation when subjected to tension. This means that even after the load is removed, the material will not return to its original shape. This is in contrast to the elastic region, where the material can undergo temporary deformation and return to its original shape once the load is removed. Therefore, it is true that there is permanent damage in the plastic region for tension.

Explanation

In the plastic region, the material undergoes permanent deformation when subjected to tension. This means that even after the load is removed, the material will not return to its original shape. This is in contrast to the elastic region, where the material can undergo temporary deformation and return to its original shape once the load is removed. Therefore, it is true that there is permanent damage in the plastic region for tension.

15. In tension, brittle fractures fail 90 degrees in relation to the principle direction of stress.

True

False

In tension, brittle fractures occur at a 90-degree angle to the principle direction of stress. This means that when a brittle material is subjected to tension, it tends to break perpendicular to the applied force. This behavior is characteristic of materials that have low ductility and high stiffness, such as ceramics or certain types of metals. The 90-degree angle of failure is due to the nature of the atomic bonds in these materials, which are unable to deform and instead fracture when subjected to tension.

Explanation

In tension, brittle fractures occur at a 90-degree angle to the principle direction of stress. This means that when a brittle material is subjected to tension, it tends to break perpendicular to the applied force. This behavior is characteristic of materials that have low ductility and high stiffness, such as ceramics or certain types of metals. The 90-degree angle of failure is due to the nature of the atomic bonds in these materials, which are unable to deform and instead fracture when subjected to tension.

16. In tension, ductile fractures fail at 45 degrees to the principle direction of stress.

True

False

Ductile fractures occur in materials that are capable of undergoing plastic deformation before failure. When a material is subjected to tension, it experiences stress in a specific direction. In the case of ductile fractures, the failure occurs at an angle of 45 degrees to the principle direction of stress. This is because the material undergoes significant plastic deformation and necking before it finally fractures. The 45-degree angle is a characteristic feature of ductile fractures and is observed in many materials, including metals. Therefore, the statement is true.

Explanation

Ductile fractures occur in materials that are capable of undergoing plastic deformation before failure. When a material is subjected to tension, it experiences stress in a specific direction. In the case of ductile fractures, the failure occurs at an angle of 45 degrees to the principle direction of stress. This is because the material undergoes significant plastic deformation and necking before it finally fractures. The 45-degree angle is a characteristic feature of ductile fractures and is observed in many materials, including metals. Therefore, the statement is true.

17. When a material has a cup-cone fracture, it means it has failed in shear for the tension test.

True

False

When a material has a cup-cone fracture, it means that during the tension test, the material experienced shear failure. In a tension test, a material is subjected to a tensile force, and if the material fails in shear, it indicates that the material could not withstand the applied force and fractured along a shear plane. This type of fracture is characterized by a cup-shaped depression on one side of the fracture surface and a cone-shaped protrusion on the other side. Therefore, the statement "When a material has a cup-cone fracture, it means it has failed in shear for the tension test" is true.

Explanation

When a material has a cup-cone fracture, it means that during the tension test, the material experienced shear failure. In a tension test, a material is subjected to a tensile force, and if the material fails in shear, it indicates that the material could not withstand the applied force and fractured along a shear plane. This type of fracture is characterized by a cup-shaped depression on one side of the fracture surface and a cone-shaped protrusion on the other side. Therefore, the statement "When a material has a cup-cone fracture, it means it has failed in shear for the tension test" is true.

18. For four-point bending, the top of the specimen is in compression and the bottom of the specimen is in tension

True

False

In four-point bending, the specimen is subjected to a bending moment that causes the top of the specimen to be compressed and the bottom to be stretched, resulting in tension. This is because the load is applied at two points on the top surface of the specimen, creating a downward force that causes compression on the top, while the bottom surface experiences an upward force, resulting in tension. Therefore, the statement that the top of the specimen is in compression and the bottom is in tension is true for four-point bending.

Explanation

In four-point bending, the specimen is subjected to a bending moment that causes the top of the specimen to be compressed and the bottom to be stretched, resulting in tension. This is because the load is applied at two points on the top surface of the specimen, creating a downward force that causes compression on the top, while the bottom surface experiences an upward force, resulting in tension. Therefore, the statement that the top of the specimen is in compression and the bottom is in tension is true for four-point bending.

19. The Modulus of Rupture is an estimate of ultimate strength for materials that did not break in four-point bending.

True

False

The modulus of rupture is indeed an estimate of the ultimate strength for materials that did not break in four-point bending. This means that if a material did not fracture or break when subjected to a four-point bending test, the modulus of rupture can be used as an approximation of its ultimate strength. Therefore, the statement "The Modulus of Rupture is an estimate of ultimate strength for materials that did not break in four-point bending" is true.

Explanation

The modulus of rupture is indeed an estimate of the ultimate strength for materials that did not break in four-point bending. This means that if a material did not fracture or break when subjected to a four-point bending test, the modulus of rupture can be used as an approximation of its ultimate strength. Therefore, the statement "The Modulus of Rupture is an estimate of ultimate strength for materials that did not break in four-point bending" is true.

20. Ductile fractures in tension begin with triaxial states of stress.

True

False

Also know that the end once they return to a uniaxial state of stress.

Explanation

Also know that the end once they return to a uniaxial state of stress.

21. Aluminum experiences an "orange peel" effect on deformed surfaces.

True

False

The "orange peel" effect refers to a surface texture that resembles the bumpy and uneven texture of an orange peel. Aluminum can experience this effect on deformed surfaces, meaning that when aluminum is deformed or shaped, it can develop a textured surface that resembles the texture of an orange peel. Therefore, the statement "Aluminum experiences an 'orange peel' effect on deformed surfaces" is true.

Explanation

The "orange peel" effect refers to a surface texture that resembles the bumpy and uneven texture of an orange peel. Aluminum can experience this effect on deformed surfaces, meaning that when aluminum is deformed or shaped, it can develop a textured surface that resembles the texture of an orange peel. Therefore, the statement "Aluminum experiences an 'orange peel' effect on deformed surfaces" is true.

22. Steel can have mill scale on the specimen.

True

False

Mill scale is a dark oxide layer that forms on the surface of steel during the hot rolling process. It is a byproduct of the steel manufacturing process and consists of iron oxides. Therefore, it is true that steel can have mill scale on the specimen.

Explanation

Mill scale is a dark oxide layer that forms on the surface of steel during the hot rolling process. It is a byproduct of the steel manufacturing process and consists of iron oxides. Therefore, it is true that steel can have mill scale on the specimen.

23. In compression, there is both a uniform stress distribution and a uniaxial state of stress until buckling.

True

False

The statement is true because in compression, the stress is distributed uniformly across the material, meaning that the force is evenly spread out. Additionally, there is a uniaxial state of stress, which means that the stress is applied in only one direction. This remains true until buckling occurs, which is when the material starts to bend or collapse under the compressive force.

Explanation

The statement is true because in compression, the stress is distributed uniformly across the material, meaning that the force is evenly spread out. Additionally, there is a uniaxial state of stress, which means that the stress is applied in only one direction. This remains true until buckling occurs, which is when the material starts to bend or collapse under the compressive force.

24. Small radius notches have higher stress concentrations.

True

False

Small radius notches have higher stress concentrations because they create a sharp change in geometry, leading to a localized increase in stress. This is due to the stress being concentrated at the tip of the notch, resulting in a higher stress concentration factor compared to larger radius notches. As a result, smaller radius notches are more likely to experience failure or fracture under stress.

Explanation

Small radius notches have higher stress concentrations because they create a sharp change in geometry, leading to a localized increase in stress. This is due to the stress being concentrated at the tip of the notch, resulting in a higher stress concentration factor compared to larger radius notches. As a result, smaller radius notches are more likely to experience failure or fracture under stress.

25. Match the following

Barreling

Buckling

Submit

26. Steel behaves ductile in tension.

True

False

Steel is known for its high ductility, which means it can be stretched or deformed without breaking. When subjected to tension or pulling forces, steel can elongate significantly before reaching its breaking point. This property makes steel an excellent material for structural applications, as it can absorb energy and withstand loads without sudden failure. Therefore, the statement that steel behaves ductile in tension is correct.

Explanation

Steel is known for its high ductility, which means it can be stretched or deformed without breaking. When subjected to tension or pulling forces, steel can elongate significantly before reaching its breaking point. This property makes steel an excellent material for structural applications, as it can absorb energy and withstand loads without sudden failure. Therefore, the statement that steel behaves ductile in tension is correct.

27. Yielding is a type of failure.

True

False

Yielding refers to the deformation or bending of a material under stress without fracturing or breaking. It is considered a type of failure because the material does not retain its original shape or strength when subjected to excessive stress. This can lead to structural instability or compromised performance, making it a form of failure in engineering and materials science.

Explanation

Yielding refers to the deformation or bending of a material under stress without fracturing or breaking. It is considered a type of failure because the material does not retain its original shape or strength when subjected to excessive stress. This can lead to structural instability or compromised performance, making it a form of failure in engineering and materials science.

28. For Rockwell Hardness: Scale C is for soft materials whereas Scale B is for hard materials.

True

False

Switch the two

Explanation

Switch the two

29. In tension there is a uniform stress state in the plastic region.

True

False

Uniform prior to necking but not after

Explanation

Uniform prior to necking but not after

30. Rockwell is a preferred test for materials that require averaged impurities.

True

False

Brinell

Explanation

Brinell

31. Young's Modulus, yield strength, and ductility are all dependent on one another.

True

False

Not all necessarily related

Explanation

Not all necessarily related

32. Cast Iron has a linear elastic region in tension.

True

False

Need to use secant modulus which implies nonlinear

Explanation

Need to use secant modulus which implies nonlinear

33. Yielding is found using the secant modulus.

True

False

They are unrelated

Explanation

They are unrelated

34. Brinell Hardness is only useful on homogeneous materials.

True

False

Actually more useful on heterogeneous materials

Explanation

Actually more useful on heterogeneous materials

35. Materials that are ductile in tension have brittle behavior in torsion.

True

False

This statement is false. Materials that are ductile in tension generally exhibit ductile behavior in torsion as well. Ductility refers to the ability of a material to deform plastically without fracturing. If a material is ductile in tension, it means it can undergo significant plastic deformation before breaking. This characteristic is usually consistent across different types of loading, including torsion. Therefore, materials that are ductile in tension are also likely to exhibit ductile behavior in torsion.

Explanation

This statement is false. Materials that are ductile in tension generally exhibit ductile behavior in torsion as well. Ductility refers to the ability of a material to deform plastically without fracturing. If a material is ductile in tension, it means it can undergo significant plastic deformation before breaking. This characteristic is usually consistent across different types of loading, including torsion. Therefore, materials that are ductile in tension are also likely to exhibit ductile behavior in torsion.

36. For tension, Young's Modulus relates stress to strain in the plastic region.

True

False

This is found in the elastic region.

Explanation

This is found in the elastic region.

37. Cast Iron has similar characteristics in tension and compression.

True

False

Think stacks of paper

Explanation

Think stacks of paper

38. The number given by a Rockwell Hardness test is relative to the diameter of the indentation.

True

False

It is in relation to the depth of indentation

Explanation

It is in relation to the depth of indentation

39. Match the following:

Engineering Stress

True Stress

Submit

40. In notch bending as Kt increases, load and energy also increase.

True

False

As Kt decreases

Explanation

As Kt decreases

41. Elastic modulus can only be found for materials with linear relationships.

True

False

The statement is false because the elastic modulus can be found for both materials with linear relationships and materials with non-linear relationships. The elastic modulus is a measure of a material's stiffness and its ability to deform under stress. It is applicable to a wide range of materials, including both linear and non-linear materials. Therefore, the statement that elastic modulus can only be found for materials with linear relationships is incorrect.

Explanation

The statement is false because the elastic modulus can be found for both materials with linear relationships and materials with non-linear relationships. The elastic modulus is a measure of a material's stiffness and its ability to deform under stress. It is applicable to a wide range of materials, including both linear and non-linear materials. Therefore, the statement that elastic modulus can only be found for materials with linear relationships is incorrect.

42. True stress is valid for the entire curve of a ductile material in tension.

True

False

Assume uniform deformation

Explanation

Assume uniform deformation

43. Can the elastic modulus be approximated for some materials using the 0.2% yield strength method?

True

False

Secant Modulus

Explanation

Secant Modulus

44. Match:

Material has yielded

Material has not yielded

Submit

45. There is a volume change in torsion testing.

True

False

In torsion testing, the volume of the material remains constant. Torsion testing involves twisting a specimen to measure its resistance to twisting forces. During this process, the material experiences shear stress and strain, but there is no change in volume. Therefore, the statement that there is a volume change in torsion testing is false.

Explanation

In torsion testing, the volume of the material remains constant. Torsion testing involves twisting a specimen to measure its resistance to twisting forces. During this process, the material experiences shear stress and strain, but there is no change in volume. Therefore, the statement that there is a volume change in torsion testing is false.

46. An example of Poisson's effect is when we pull something in one direction, it gets larger in the other.

True

False

It would get smaller in the other direction

Explanation

It would get smaller in the other direction

47. PMMA is most sensitive to a notch in compression.

True

False

PMMA, or polymethyl methacrylate, is a type of plastic that is commonly used in various applications. It is known for its high impact resistance and is often used as a substitute for glass. However, PMMA is not particularly sensitive to notches in compression. In fact, it is more sensitive to notches in tension. This means that when PMMA is subjected to a tensile force, such as stretching or pulling, a notch or crack in the material is more likely to propagate and cause failure. Therefore, the correct answer is false.

Explanation

PMMA, or polymethyl methacrylate, is a type of plastic that is commonly used in various applications. It is known for its high impact resistance and is often used as a substitute for glass. However, PMMA is not particularly sensitive to notches in compression. In fact, it is more sensitive to notches in tension. This means that when PMMA is subjected to a tensile force, such as stretching or pulling, a notch or crack in the material is more likely to propagate and cause failure. Therefore, the correct answer is false.

48. Brittle materials are weak in the shear direction and ductile materials are weak in tension.

True

False

Reverse

Explanation

Reverse

49. Aluminum has an upper and lower yield.

True

False

Aluminum does not have an upper and lower yield. Yield strength refers to the point at which a material begins to deform plastically, and aluminum does not exhibit a distinct upper and lower yield like some other materials. Instead, aluminum has a single yield strength value that represents the point at which it undergoes plastic deformation. Therefore, the correct answer is False.

Explanation

Aluminum does not have an upper and lower yield. Yield strength refers to the point at which a material begins to deform plastically, and aluminum does not exhibit a distinct upper and lower yield like some other materials. Instead, aluminum has a single yield strength value that represents the point at which it undergoes plastic deformation. Therefore, the correct answer is False.

50. Small radius notches cause the specimens to fail at higher energy than notches with a larger radius.

True

False

Low load, low energy

Explanation

Low load, low energy

51. Cast Iron is a heterogeneous material.

True

False

Cast iron is a heterogeneous material because it is composed of multiple phases, including iron and carbon. The carbon is present in the form of graphite flakes or nodules, which are dispersed throughout the iron matrix. This non-uniform distribution of carbon gives cast iron its characteristic properties, such as high strength and wear resistance. Additionally, cast iron may contain other elements and impurities that further contribute to its heterogeneity.

Explanation

Cast iron is a heterogeneous material because it is composed of multiple phases, including iron and carbon. The carbon is present in the form of graphite flakes or nodules, which are dispersed throughout the iron matrix. This non-uniform distribution of carbon gives cast iron its characteristic properties, such as high strength and wear resistance. Additionally, cast iron may contain other elements and impurities that further contribute to its heterogeneity.

52. In tension, brittle failures are associated with cup-cone failures.

True

False

Brittle failures are not associated with cup-cone failures in tension. Cup-cone failures occur in ductile materials, where the material stretches and forms a cup-shaped depression before finally breaking. Brittle failures, on the other hand, occur without any significant deformation or warning and result in sudden fracture. Therefore, the correct answer is false.

Explanation

Brittle failures are not associated with cup-cone failures in tension. Cup-cone failures occur in ductile materials, where the material stretches and forms a cup-shaped depression before finally breaking. Brittle failures, on the other hand, occur without any significant deformation or warning and result in sudden fracture. Therefore, the correct answer is false.

53. In tension, brittle failures are characterized by a large change in cross sectional area.

True

False

Brittle failures are not characterized by a large change in cross-sectional area. In fact, brittle materials tend to fail with little or no plastic deformation, resulting in a small or negligible change in cross-sectional area. This is in contrast to ductile materials, which deform significantly before failure and exhibit a large change in cross-sectional area. Therefore, the correct answer is False.

Explanation

Brittle failures are not characterized by a large change in cross-sectional area. In fact, brittle materials tend to fail with little or no plastic deformation, resulting in a small or negligible change in cross-sectional area. This is in contrast to ductile materials, which deform significantly before failure and exhibit a large change in cross-sectional area. Therefore, the correct answer is False.

54. A material must yield in order for 0.2% Offset Yield Strength Method to be valid.

True

False

The 0.2% Offset Yield Strength Method is a way to determine the yield strength of a material. In this method, a small amount of offset is applied to the stress-strain curve, typically 0.2%, to ensure that the material has yielded. If the material does not yield, the method cannot be validly used to determine its yield strength. Therefore, the statement that a material must yield in order for the 0.2% Offset Yield Strength Method to be valid is true.

Explanation

The 0.2% Offset Yield Strength Method is a way to determine the yield strength of a material. In this method, a small amount of offset is applied to the stress-strain curve, typically 0.2%, to ensure that the material has yielded. If the material does not yield, the method cannot be validly used to determine its yield strength. Therefore, the statement that a material must yield in order for the 0.2% Offset Yield Strength Method to be valid is true.

55. Ductile fractures are associated with non-uniform deformation of the specimen.

True

False

Ductile fractures occur when a material undergoes significant plastic deformation before breaking. This means that the material can stretch and change shape without immediately fracturing. Non-uniform deformation refers to the fact that the material deforms more in certain areas than others, leading to variations in the stress and strain distribution. Therefore, it is true that ductile fractures are associated with non-uniform deformation of the specimen.

Explanation

Ductile fractures occur when a material undergoes significant plastic deformation before breaking. This means that the material can stretch and change shape without immediately fracturing. Non-uniform deformation refers to the fact that the material deforms more in certain areas than others, leading to variations in the stress and strain distribution. Therefore, it is true that ductile fractures are associated with non-uniform deformation of the specimen.

56. In four point bending, there is a non-uniform stress state across the cross section.

True

False

In four point bending, the bending load is applied at two points on the top surface and two points on the bottom surface of the beam. This results in a non-uniform stress distribution across the cross section of the beam. The top surface experiences compressive stresses near the load points, while the bottom surface experiences tensile stresses. The stress distribution gradually changes from compression to tension as we move away from the load points. Therefore, it is true that in four point bending, there is a non-uniform stress state across the cross section.

Explanation

In four point bending, the bending load is applied at two points on the top surface and two points on the bottom surface of the beam. This results in a non-uniform stress distribution across the cross section of the beam. The top surface experiences compressive stresses near the load points, while the bottom surface experiences tensile stresses. The stress distribution gradually changes from compression to tension as we move away from the load points. Therefore, it is true that in four point bending, there is a non-uniform stress state across the cross section.

57. Brinell Hardness is useful for both soft and hard materials.

True

False

Brinell Hardness is a method used to measure the hardness of materials by applying a known load to the surface of the material and measuring the diameter of the resulting indentation. This method is suitable for both soft and hard materials because it uses a relatively large indenter and a heavy load, making it effective in measuring the hardness of materials with varying degrees of hardness. Therefore, the statement "Brinell Hardness is useful for both soft and hard materials" is true.

Explanation

Brinell Hardness is a method used to measure the hardness of materials by applying a known load to the surface of the material and measuring the diameter of the resulting indentation. This method is suitable for both soft and hard materials because it uses a relatively large indenter and a heavy load, making it effective in measuring the hardness of materials with varying degrees of hardness. Therefore, the statement "Brinell Hardness is useful for both soft and hard materials" is true.

58. As area increases, stress decreases in notch bending.

True

False

In notch bending, the presence of a notch or a groove in a material causes stress concentration. When the area of the material surrounding the notch increases, the stress is distributed over a larger area, resulting in a decrease in stress concentration. Therefore, as the area increases, the stress decreases in notch bending.

Explanation

In notch bending, the presence of a notch or a groove in a material causes stress concentration. When the area of the material surrounding the notch increases, the stress is distributed over a larger area, resulting in a decrease in stress concentration. Therefore, as the area increases, the stress decreases in notch bending.

59. For four point bending, zero bending moment is between the inner contact points.

True

False

The beam is in a constant bending moment.

Explanation

The beam is in a constant bending moment.

60. The elastic region always obeys Hooke's Law in tension.

True

False

PMMA and Cast Iron show otherwise

Explanation

PMMA and Cast Iron show otherwise

61. All materials were strengthened by notches except PMMA in tension (down).

True

False

The statement suggests that all materials, except PMMA, were strengthened by notches in tension. This means that the presence of notches improved the strength of these materials when subjected to tension forces. Since the statement says "except PMMA," it implies that PMMA did not experience the same strengthening effect from notches in tension. Therefore, the correct answer is True.

Explanation

The statement suggests that all materials, except PMMA, were strengthened by notches in tension. This means that the presence of notches improved the strength of these materials when subjected to tension forces. Since the statement says "except PMMA," it implies that PMMA did not experience the same strengthening effect from notches in tension. Therefore, the correct answer is True.