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Types of Stress and Strain

19 questions

All types19Multiple choice10True / False6Matching3
Question 1Question →

Match each mechanical action or scenario to the primary type of internal stress it induces on the object or material.

Click a left item, then click its matching right item

Items

A pneumatic press crushing and flattening a scrap car.
A power drill driving a long, thick screw into a wooden beam.
A chain hoist suspending a heavy engine block in mid-air.
A pair of aviation snips cutting through a sheet of aluminum.

Matches

Show answer & explanation

Answer

The pneumatic press causes Compressive stress; the power drill causes Torsional stress; the chain hoist causes Tensile stress; and the aviation snips cause Shear stress.
Each scenario correctly matches the fundamental definition of the applied stress. The press pushes inward (compression), the drill twists the fastener (torsion), the hoist pulls outward on the chain (tension), and the snips cut by applying parallel opposing forces (shear).

Step-by-Step Solution

1
Analyze the forces acting on the scrap car in the pneumatic press.
The press pushes the car from opposite sides, squeezing it.
Identifying the direction of force determines the stress type. Pushing forces create compressive stress.
2
Analyze the forces on the screw being driven by a power drill.
The drill twists the screw along its longitudinal axis.
Twisting forces create torsional stress.
3
Analyze the forces on the chain hoist suspending the engine block.
The chain is pulled apart by the weight of the engine downward and the support upward.
Pulling forces that stretch an object create tensile stress.
4
Analyze the forces acting on the aluminum sheet when cut by aviation snips.
The blades push the material in opposite directions along a single plane, slicing it.
Parallel opposing forces that cause material to slide or cut create shear stress.

Key Concept

Different types of mechanical stress are defined by how forces are applied to a material: pulling (tension), pushing (compression), sliding or cutting (shear), and twisting (torsion).
Question 2Question →

A heavy steel block is being lifted vertically by a crane using a single wire cable. As the block hangs from the cable, what type of internal stress is primarily acting on the cable?

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Answer: Tension

Answer

Tension
The correct answer identifies that the cable is being pulled from opposite directions along its axis (upward by the crane, downward by the block). This pulling action attempts to stretch the cable, which defines tensile stress or tension.

Step-by-Step Solution

1
Analyze the external forces acting on the cable.
The crane pulls upward on the cable, while the heavy block pulls downward due to gravity.
Identifying the direction of external forces is necessary to determine the resulting internal stress.
2
Determine how these forces affect the material.
The upward and downward forces pull in opposite directions, attempting to stretch or elongate the cable.
Matching the force pattern (pulling, pushing, sliding, twisting) reveals the stress type.
3
Identify the correct engineering term for this stress.
The stretching force is known as tension.
Tension is defined as the stress resulting from forces that act to pull a material apart.

Key Concept

Tension is the internal stress created when outward pulling forces act to stretch a structural component.
Question 3Question →

A simple wall-mounted jib crane is used to lift a heavy engine block. The crane consists of a rigid horizontal beam attached to a vertical wall at one end, and a diagonal support cable connecting the outer end of the beam to a point higher up on the wall. The engine block hangs directly from the outer end of the horizontal beam. Based on this configuration, which of the following correctly identifies the primary type of stress experienced by the diagonal cable and the horizontal beam?

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Answer: The cable is in tension; the beam is in compression.

Answer

The diagonal cable experiences tension, and the horizontal beam experiences compression.
The heavy load pulls down on the outer connection point. The diagonal cable resists this by pulling up and in toward the wall, putting the cable in tension. To counteract the inward pull of the cable, the horizontal beam is squeezed against the wall, putting the beam in compression.

Step-by-Step Solution

1
Analyze the forces acting on the outer end of the horizontal beam.
The suspended load creates a downward force at the connection point.
Identifying the primary external force is necessary to determine internal member stresses.
2
Determine the stress on the diagonal support cable.
To prevent the beam from falling, the cable must pull upward and backward toward the wall. This stretching force means the cable is in tension.
Cables can only support pulling forces (tension); they would buckle under pushing forces.
3
Determine the stress on the horizontal beam.
Because the cable is pulling backward toward the wall, the horizontal beam must push outward to keep the system in equilibrium. This squeezing force means the beam is in compression.
Structural members that are squeezed between opposing forces undergo compressive stress.

Key Concept

Tension and Compression in Structural Members
Estimated Time:45s
Question 4Question →

A building's concrete foundation pillars, which support the heavy weight of the entire structure above them, are primarily subjected to tension stress.

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Answer: False

Answer

False
The statement is false because foundation pillars are pushed down upon by the immense weight of the building they support. This squeezing action produces compression stress. Tension stress only occurs when a material is being pulled or stretched.

Step-by-Step Solution

1
Analyze the forces acting on the foundation pillars.
The pillars support the weight of the building pushing down on them from above.
Identifying the direction and nature of the force is necessary to determine the specific type of stress.
2
Determine the type of stress caused by this specific force.
The downward force of the building squeezes the pillars against the ground. This squeezing action is defined as compression.
Tension is a pulling force that stretches a material, while compression is a pushing force that squeezes or compacts it.

Key Concept

Compression vs. Tension Stress
Estimated Time:30s
Question 5Question →

When a simply supported horizontal beam bends downward due to a heavy load applied at its center, the top surface of the beam experiences tensile stress, while the bottom surface experiences compressive stress.

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Answer: False

Answer

False
When a simply supported horizontal beam bends downward, it forces the material on the top surface to push together and the material on the bottom surface to stretch apart. Therefore, the top experiences compressive stress and the bottom experiences tensile stress, making the statement false.

Step-by-Step Solution

1
Visualize the deformation of the beam under the central load.
The beam bows downward in the center, creating a U-like curvature.
Understanding the physical deformation is the first step to identifying the internal stresses.
2
Identify the effect on the top surface of the bent beam.
The top surface curves inward, causing its overall length to effectively shorten.
When a material's fibers are pushed together or shortened, it is under compressive stress.
3
Identify the effect on the bottom surface of the bent beam.
The bottom surface curves outward, causing its overall length to stretch.
When a material's fibers are pulled apart or elongated, it is under tensile stress.

Key Concept

Bending Stress in Structural Members
Estimated Time:30s
Question 6Question →

A solid drive shaft transmits rotational power to a heavy gear. To lock them together and prevent the gear from slipping, a rectangular steel key is fitted into a shared horizontal slot between the shaft and the gear's inner hub. When the motor engages and the shaft forcefully rotates while the heavy gear resists, the shaft pushes against one side of the key's bottom half, while the gear's hub pushes back against the opposite side of the key's top half. What primary type of mechanical stress does the steel key experience in this scenario?

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Answer: Shear stress

Answer

Shear stress
The correct answer accurately identifies that the key experiences two opposing forces acting on parallel, offset planes. The shaft pushes one half, and the gear pushes the other. This creates a cutting or sliding effect along the horizontal plane between the two halves, which is the exact definition of shear stress.

Step-by-Step Solution

1
Analyze the forces acting on the specific component in question (the steel key).
The shaft pushes the bottom half of the key in the direction of rotation, while the gear hub resists, pushing the top half of the key in the opposite direction.
Accurate force identification is the first step in determining internal stress.
2
Evaluate the alignment of these opposing forces.
The forces act parallel to each other but on slightly offset planes (top half vs. bottom half).
The alignment of the load dictates how the material will tend to deform.
3
Match the observed force pattern to standard mechanical stress definitions.
Opposing forces acting on offset, parallel planes attempt to slide one portion of the material over another, which defines shear stress.
This confirms the correct classification of the mechanical load.

Key Concept

Identifying Shear Stress in Fasteners and Load-Bearing Joints
Question 7Question →

Two overlapping steel plates are fastened together by a single rivet. If opposing lateral forces pull the two plates in opposite directions away from each other, what type of internal stress is primarily experienced by the rivet?

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Answer: Shear stress

Answer

Shear stress
The forces from the plates act in parallel but opposite directions across the cross-section of the rivet. This attempts to slide the top half of the rivet off the bottom half, which perfectly describes shear stress (similar to how a pair of shears cuts paper).

Step-by-Step Solution

1
Analyze the direction of the external forces acting on the joint.
The plates are being pulled in opposite directions, parallel to their mating surfaces.
Identifying the force vectors is necessary to determine how they interact with the fastener.
2
Determine how these forces translate to the rivet.
The top plate pushes against the top half of the rivet in one direction, while the bottom plate pushes against the bottom half in the opposite direction.
This cross-sectional cutting action defines the type of stress on the internal component.
3
Match the physical action to the definition of structural stresses.
Forces causing internal layers of a material to slide past each other create shear stress.
Applying the standard definition of shear stress in mechanical systems yields the final answer.

Key Concept

Types of Stress and Strain
Estimated Time:30s
Question 8Question →

Match each type of mechanical stress to the description of the forces that cause it.

Click a left item, then click its matching right item

Items

Tension
Compression
Shear
Torsion

Matches

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Answer

Tension matches stretching forces, Compression matches squeezing forces, Shear matches unaligned parallel forces causing sliding, and Torsion matches twisting forces.
Each type of stress is strictly defined by the nature of the applied load: outward pulling causes tension, inward pushing causes compression, unaligned sliding forces cause shear, and twisting causes torsion.

Step-by-Step Solution

1
Analyze 'Tension'
Matches with pulling and stretching forces.
By definition, tensile stress elongates materials.
2
Analyze 'Compression'
Matches with pushing and squeezing forces.
By definition, compressive stress shortens materials.
3
Analyze 'Shear'
Matches with unaligned parallel forces.
Shear forces act like scissors, pushing adjacent planes of material in opposite directions.
4
Analyze 'Torsion'
Matches with twisting forces.
Torsional stress is applied rotationally around an axis.

Key Concept

Identifying the primary types of mechanical stress based on the direction and application of applied forces.
Estimated Time:45s
Question 9Question →

A heavy shipping container is suspended steadily in the air by a single vertical steel cable attached to a helicopter. Which of the following types of stress is the steel cable primarily experiencing?

Show answer & explanation

Answer: Tension

Answer

Tension
The correct answer is tension because the cable is subjected to opposing forces pulling outward from its center (the lifting force of the helicopter above and the weight of the container below). This pulling action tends to stretch or elongate the material, which is the exact definition of tensile stress.

Step-by-Step Solution

1
Identify the direction of the forces acting on the cable.
The helicopter exerts an upward force on the top of the cable, while gravity acting on the shipping container exerts a downward force on the bottom of the cable.
Understanding the direction of applied forces is required to determine the type of stress.
2
Determine how these forces affect the material of the cable.
The opposing outward forces pull the cable from both ends, attempting to stretch or elongate it.
Matching the physical effect to the definition of stress types reveals the answer.
3
Match the stretching effect to the correct stress terminology.
A pulling force that stretches a material is defined as tension.
Tension is the specific mechanical term for this type of load.

Key Concept

Types of Mechanical Stress (Tension)
Question 10Question →

Match each structural scenario or mechanical component to the primary type of internal stress it experiences under load.

Click a left item, then click its matching right item

Items

A heavy load pushing directly down on a vertical concrete foundation pillar
A tightly stretched crane cable actively lifting a heavy steel beam
A solid metal drive shaft transmitting rotational power from an engine to a vehicle's wheels
A single structural bolt connecting two overlapping metal plates that are being pulled in opposite directions

Matches

Show answer & explanation

Answer

Concrete pillar matches to Compressive stress; crane cable matches to Tensile stress; drive shaft matches to Torsional stress; bolt holding overlapping plates matches to Shear stress.
Structural and mechanical components are designed to withstand specific forces based on their application. Pillars support weight by resisting being crushed (compression). Cables lift loads by resisting being stretched (tension). Drive shafts transmit torque by resisting being twisted (torsion). Fasteners like bolts hold sliding members together by resisting being cut in half (shear).

Step-by-Step Solution

1
Analyze the force acting on the concrete foundation pillar.
The pillar is being pushed down upon, which squeezes the material.
Pushing forces that attempt to shorten or crush a material create compressive stress.
2
Analyze the force acting on the crane cable.
The cable is being pulled from both ends by the crane mechanism and the load.
Pulling forces that attempt to stretch or elongate a material create tensile stress.
3
Analyze the force acting on the drive shaft.
The shaft is being rotated rapidly to transmit power, creating a twisting motion.
Twisting forces applied to an object create torsional stress.
4
Analyze the force acting on the structural bolt.
The overlapping plates pull in opposite directions, acting like scissors across the middle of the bolt.
Forces acting parallel to a cross-section, attempting to slice or cut the material, create shear stress.

Key Concept

Different types of external loads applied to structural components result in specific types of internal stresses: tension (pulling apart), compression (pushing together), torsion (twisting), and shear (slicing across).
Question 11Question →

Compressive stress is the internal force that occurs when a structural component is pulled apart or stretched from both ends.

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Answer: False

Answer

False
The statement is false because the forces described (pulling apart or stretching) cause tensile stress. Compressive stress involves pushing forces that squeeze a material together.

Step-by-Step Solution

1
Analyze the definition of compressive stress.
Compressive stress is caused by pushing or squeezing forces that act to shorten a material.
To understand the physical phenomenon of compression.
2
Compare the actual definition with the given statement.
The statement describes a material being 'pulled apart or stretched', which is the definition of tensile stress, not compressive stress.
To conclude whether the statement is factually true or false.

Key Concept

Identifying Types of Structural Stress
Estimated Time:30s
Question 12Question →

In structural mechanics, strain is defined as the internal force per unit area that a material exerts to resist an applied load, whereas stress is the physical deformation or change in dimensions resulting from that applied force.

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Answer: False

Answer

False
The statement is false because it completely reverses the engineering definitions. In mechanical comprehension, stress is the internal resisting force per unit area within a material caused by an external load. Strain, on the other hand, is the physical deformation, stretching, or change in dimensions that occurs as a response to that stress.

Step-by-Step Solution

1
Analyze the definition provided for strain in the statement.
The statement claims strain is the 'internal force per unit area'.
To verify if the first half of the statement is factually accurate.
2
Analyze the definition provided for stress in the statement.
The statement claims stress is the 'physical deformation or change in dimensions'.
To verify if the second half of the statement is factually accurate.
3
Compare the provided definitions with established mechanical principles.
The definitions are completely reversed. Stress is the force per unit area, and strain is the resulting deformation.
To determine the final truth value of the entire statement.

Key Concept

Distinguishing Stress and Strain
Question 13Question →

A stationary jib crane consists of a horizontal metal boom attached to a vertical mast. The outer end of the boom is supported by a diagonal steel cable connected higher up on the mast. When a heavy load is suspended from the outer end of the boom, what types of internal stress are primarily experienced by the diagonal cable and the horizontal boom, respectively?

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Answer: Tension in the cable and compression in the boom

Answer

Tension in the cable and compression in the boom
The heavy load pulls down on the end of the boom. To support this, the diagonal cable must pull upward and inward toward the mast, which stretches the cable, resulting in tensile stress (tension). The inward horizontal component of the cable's pull pushes the boom horizontally into the mast. This pushing force squeezes the boom, resulting in compressive stress (compression).

Step-by-Step Solution

1
Analyze the forces acting on the diagonal cable.
The downward weight of the load causes the cable to pull back against it to keep the boom from falling.
Identifying the force direction determines the stress. Pulling forces acting along the length of a material create tension.
2
Analyze the forces acting on the horizontal boom.
The diagonal cable pulls inward toward the mast. This inward horizontal force pushes the boom tightly against the mast.
Pushing or crushing forces acting along the axis of a structural member create compression.

Key Concept

Identifying tension and compression in load-bearing structural members.
Question 14Question →

A marine vessel is cruising forward at a constant speed. Its propulsion system uses an internal engine to drive a solid steel shaft, which extends out the rear of the hull to turn the propeller. A heavy-duty thrust bearing inside the ship absorbs the forward driving force generated by the propeller. During this forward motion, what primary combination of internal stresses is the section of the shaft located between the propeller and the thrust bearing experiencing?

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Answer: Torsion and compression

Answer

Torsion and compression
The correct answer is torsion and compression because the engine twists the shaft to rotate the propeller (creating torsion), and the forward thrust generated by the propeller pushes the shaft into the internal thrust bearing (creating compression).

Step-by-Step Solution

1
Identify the stress caused by power transmission.
The engine applies a rotational force to turn the propeller against water resistance, resulting in twisting, which is torsional stress.
Rotational power transmission through a solid shaft always induces torsion.
2
Determine the direction of the thrust force.
To move the ship forward, the propeller pushes water backward. According to Newton's Third Law, the water exerts an equal forward reaction force on the propeller.
Thrust requires an opposing reaction force to generate motion.
3
Analyze how the thrust force affects the shaft.
The forward reaction force on the propeller pushes the shaft forward into the thrust bearing inside the hull. This squeezes the section of the shaft between them, creating compressive stress.
A structural member being squeezed inward from opposite ends is under compression.

Key Concept

Internal stresses induced by combined rotational and axial loads.
Question 15Question →

A rigid horizontal strut extends outward from a vertical building wall to support a heavy sign. The outer end of the strut is supported by a diagonal steel cable anchored to the wall above. The inner end of the strut is connected to a wall bracket using a heavy-duty steel pin. When the sign's weight is applied to the outer end of the strut, what primary types of internal mechanical stress are experienced by the diagonal cable, the horizontal strut, and the steel pin, respectively?

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Answer: Cable: Tension; Strut: Compression; Pin: Shear

Answer

The correct answer identifies the cable under tension, the strut under compression, and the pin under shear.
The correct answer accurately evaluates the stress on all three components. The diagonal cable must stretch to hold up the heavy sign, placing it under tension. This tension has an inward horizontal pull, which squeezes the horizontal strut against the wall, creating compressive stress. Finally, the downward weight acting on the wall bracket tries to slide or slice perpendicularly across the steel pin, subjecting it to shear stress.

Step-by-Step Solution

1
Analyze the forces acting on the diagonal cable.
The cable must pull upward and backward toward the wall to support the downward weight of the sign.
Supporting a downward load from above requires an upward pulling force, which stretches the material and creates tension.
2
Analyze the forces acting on the horizontal strut.
The inward horizontal component of the cable's tension pulls the outer end of the strut firmly against the wall.
Because the strut is being squeezed between the cable's attachment point and the wall bracket, it experiences compressive stress.
3
Analyze the forces acting on the wall bracket pin.
The downward weight of the strut and load pushes perpendicularly against the cross-section of the connecting pin.
Forces acting parallel to the cross-section of a fastener, trying to slice through it, cause shear stress.

Key Concept

Identifying applied structural loads (Tension, Compression, Shear)
Question 16Question →

A worker stands on the top platform of an open A-frame stepladder resting on a smooth floor. The ladder has a horizontal folding metal spreader bar that connects the front and rear legs to keep the ladder from collapsing flat. What primary type of internal stress is experienced by the horizontal spreader bar while supporting the worker's weight?

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Answer: Tension

Answer

Tension
When a downward load is applied to an A-frame ladder, the angled legs tend to spread outward. The horizontal spreader bar counteracts this by holding the legs together. Because the legs pull outward on both ends of the bar, the bar experiences a pulling force along its length. A force that pulls or stretches a material is defined as tension.

Step-by-Step Solution

1
Analyze the external forces acting on the ladder.
The downward force (worker's weight) pushes the ladder into the ground.
To determine how the entire structure distributes the load.
2
Determine the direction of movement the legs would take without the spreader bar.
The downward weight causes the angled front and rear legs to try to splay or slide outward away from each other on the smooth floor.
Understanding the tendency of movement reveals what the supporting member must resist.
3
Identify the opposing force exerted by the spreader bar.
The spreader bar must hold the legs together, meaning it is being pulled outward from both ends by the spreading legs.
Identifying the force acting on the component determines the type of stress.
4
Classify the internal stress based on the pulling force.
A pulling force acting along the longitudinal axis of a member creates tensile stress (tension).
This matches the definition of tension.

Key Concept

Identifying tension in structural members resisting outward forces
Estimated Time:45s
Question 17Question →

When a solid cylindrical drive shaft transmits rotational power (torque), the internal shear stress generated by the torsion is at its maximum at the central longitudinal axis of the shaft and decreases to zero at its outer surface.

Show answer & explanation

Answer: False

Answer

False
When a solid shaft is subjected to torsion, the internal shear stress is directly proportional to the distance from the central axis. This means the central longitudinal axis experiences zero stress, while the extreme outer surface of the shaft experiences the maximum shear stress.

Step-by-Step Solution

1
Identify the type of internal stress applied to the drive shaft.
The transmission of torque induces torsional shear stress within the material of the solid cylindrical shaft.
Understanding the loading condition is required to determine the structural stress distribution profile.
2
Recall the principles of torsional mechanics regarding stress distribution across a cross-section.
In a solid circular shaft, shear strain increases linearly with the radial distance from the central longitudinal axis.
This fundamental rule dictates where the material experiences the highest and lowest levels of stress.
3
Determine the locations of maximum and minimum shear stress.
At the central axis (where radius equals zero), the shear stress is zero. At the outer surface (where radius is at its maximum), the shear stress is at its absolute maximum.
To establish the factual reality of the stress distribution under torsion.
4
Evaluate the provided statement against the factual stress distribution.
The statement claims the exact opposite of reality (asserting maximum stress is at the center and zero at the surface). Therefore, the statement is false.
To derive the final answer for the true/false evaluation.

Key Concept

Torsional Shear Stress Distribution
Question 18Question →

As long as the applied tensile stress on a structural steel tie-rod remains below its ultimate tensile strength, the rod will undergo only elastic deformation and will completely return to its original length when the load is removed.

Show answer & explanation

Answer: False

Answer

False
The correct answer is False. A material only returns completely to its original dimensions if the applied stress stays below its yield strength (or elastic limit). If the applied stress exceeds the yield strength but remains below the ultimate tensile strength, the material undergoes plastic deformation, resulting in a permanent physical change.

Step-by-Step Solution

1
Analyze the mechanical properties mentioned in the statement.
The statement asserts that keeping stress below the 'ultimate tensile strength' guarantees 'elastic deformation' (returning to original length).
Identifying the specific mechanical thresholds is necessary to evaluate material deformation.
2
Compare the definitions of ultimate tensile strength and yield strength.
Yield strength marks the end of the elastic region where deformation is reversible. Ultimate tensile strength is the maximum stress the material can handle before breaking, which occurs well into the plastic (irreversible) region.
The stress-strain curve defines distinct zones of material behavior based on applied load.
3
Evaluate the statement's conclusion based on material mechanics.
If stress exceeds the yield strength but stays below the ultimate tensile strength, the tie-rod experiences plastic deformation and will not completely return to its original length.
Therefore, using ultimate tensile strength as the boundary for elastic deformation is factually incorrect.

Key Concept

Yield Strength vs. Ultimate Tensile Strength in Elastic and Plastic Deformation
Question 19Question →

A heavy machine is placed directly in the center of a horizontal steel beam that is supported only at its far left and right ends. The downward force of the machine causes the beam to bend slightly downward in the middle. Based on this load distribution, which of the following best describes the primary mechanical stresses acting on the extreme top and bottom surfaces of the beam at its midpoint?

Show answer & explanation

Answer: The top surface experiences compression, and the bottom surface experiences tension.

Answer

The top surface experiences compression, and the bottom surface experiences tension.
When a beam is supported at its ends and loaded in the center, it undergoes bending. This physical bending forces the top layers of the beam's material to crush together, generating compressive stress. Simultaneously, the bottom layers of the material are forced to stretch outward, generating tensile stress. The very center of the beam (neutral axis) experiences zero bending stress, but the extreme top and bottom surfaces experience maximum compression and tension, respectively.

Step-by-Step Solution

1
Analyze the deformation of the beam under the external load.
The central downward load causes the middle of the beam to sag, creating a slightly concave upward shape (like a shallow 'U').
Understanding the physical deformation dictates how the internal material layers are forced to move relative to one another.
2
Determine the stress on the top surface.
The top surface is on the inside of the bend, which forces its ends closer together, squeezing the material.
Forces that squeeze or crush a material generate compressive stress.
3
Determine the stress on the bottom surface.
The bottom surface is on the outside of the bend, forcing the material to elongate and stretch apart.
Forces that pull or stretch a material generate tensile stress.

Key Concept

Bending Stress Distribution in Beams
Estimated Time:45s
Types of Stress and Strain Practice Questions — Armed Services Vocational Aptitude Battery (ASVAB) | Examkin