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Worksheetsbang marjo elasticity
Total questions: 44
Worksheet time: 1hrs 1mins
What is a unit for stress?
N
N m-1
Pa
no unit
Which of the following is a correct definition for strain?
It is the length divided by the original length.
It is the extension divided by the length.
It is the extension divided by the original length.
It is the force divided by the cross-sectional area.
Which of the following is not a correct statement about strain?
It is a length divided by another length, so it has no unit.
It is always larger than 1.
It takes the same value for all objects made of the same material.
It is equal to stress divided by Young's modulus.
What is not correct about the unit for Young's modulus?
It has the same unit as stress.
It has the same unit as stiffness.
It has the same unit as pressure.
It is equal to the unit of stress divided by the unit of strain.
Which of the following is a correct expression for the Young's modulus of a wire with a circular cross-section with diameter d? The original length, extension, and force are l, Δl, and F, respectively.
πd2ΔlFl
πd2Δl4Fl
πd2lFΔl
4Flπd2Δl
The diagram shows the stress - strain curve of a material sample. Which of the following is not true?
The force - extension diagram of the sample will have a similar shape.
The sample follows Hooke's law up to a stress of 400 MPa.
The Young's modulus of the material is about 2×105 Pa.
The sample could be made from mild steel.
Which is true about the area under a stress - strain curve?
It represents the work done by the force.
It represents the work done per unit original length.
It represents the work done per unit volume.
A brittle (i.e. cracks easily) material generally has a large area below the curve.
A wire of circular cross-section, which obeys Hooke’s law, is used to suspend a basket as shown.
The Young modulus for the material of the wire is 2.5 x 1011Pa.
When a weight of 34 N is added to the basket, the strain in the wire increases by 6.0 x 10–5.
What is the radius of the wire? 9702/11/O/N/20#19
7.2 x 10–7 m
2.3 x 10–6 m
8.5 x 10–4 m
1.7 x 10–3 m
For a constant force, a rope breaks due to stress. Which of the following is useful to reduce the stress?
Increase the length of the rope
Apply small force
Increase the cross sectional area of the rope
Use a different material of rope
The stress at which extension of a material takes place more quickly as compared to increase in load, is called
No elastic zone
Plastic point
Yield point
Breaking point
What happened at point D?
The change in the internal structure of the material.
The force (stress) on the material is maximum and is known as the breaking force (stress).
This is the point where the material breaks or fractures.
What is the equation for Tensile Strain of a material?
Force / Area
Stress / Area
Extension / Length
F / A
What happens at the Yield point?
solid material that is being stretched begins to change shape permanently
material begins to elastically deform
Material is under high compressive forces and shrinks
What is the equation to calculate Young's Modulus?
Young Modulus = E = Stress/Strain
Young's Modulus = E = mc2
Youngs modulus = E =Strain/Stress
Young's Modulus = E = 1/2Fx
Definition of Plastic Deformation?
Being completely solid and not bending
'Stretching' and returning to the original shape
'Stretching' and not returning to the original shape
Falling to the floor due to lack of structure.
What is the definition of tensile strength
Resistance to localized plastic deformation induced by either mechanical indentation or abrasion.
The external force acting on an object or surface parallel to the slope or plane in which it lies
Maximum load that a material can support without fracture when being stretched.
The graph of stress against strain is always
straight line
parabola
Straight line in elastic region
parabola in elastic region
Young's modulus is property of
solids
solids and liquids
solids or liquids
gases
There are two identical wires with Young's modulus Y1 and Y2 respectively such that Y1> Y2. If they are hung from a rigid support and same weight is applied to them at their free ends then
elongation in the wires will be same
elongation in the first wire will be more
First wire will constrict more
Elongation in the second wire will be more
If you apply a force to deform a material then remove the force and the material returns to its original shape this is
elastic deformation
plastic deformation
inelastic deformation
unplastic deformation
If you apply a force to deform a material then remove the force and the material does not return to its original shape this is
elastic deformation
plastic deformation
rubber deformation
unplastic deformation
What is the stress when a force of 10N acts over a circular area of diameter 3mm?
1.4x106 Pa
3.3x10-3 Pa
3.3 Pa
354x103 Pa
A 2m wire extends by 4mm what is the strain?
0.5
2x10-3
2x10-6
0.005
What is the Youngs Modulus if a stress of 25MPa causes a strain of 0.003?
8.3 x 109 Pa
8.3 x 106 Pa
8.3 x 103 Pa
8.3 x 10-3 Pa
The diagram shows how the stress varies with strain for metal specimens X and Y which are different. Both specimens were stretched until they broke.
Which of the following is incorrect?
X is stiffer than Y
X has a higher value of the Young modulus
X is more brittle than Y
Y has a lower maximum tensile stress than X
The four bars A, B, C and D have diameters, lengths and loads as shown. They are all made of the same material. Which bar has the greatest extension?
A
B
C
D
A sample of wire has a Young modulus E. A second sample of wire made from an identical material has three times the length and half the diameter of the first sample.
What is the Young modulus of the second sample of wire in terms of E?
0.25E
E
6E
12E
A wire of length L and cross-sectional area A is stretched a distance e by a tensile force. The Young modulus of the material of the wire is E.
Which expression gives the elastic energy stored in the stretched wire?
A steel wire has a cross-sectional area 0.5 mm2. The Young modulus of steel is 2.0 × 1011 Pa. Assume the wire obeys Hooke’s law.
What load must be suspended from the wire to produce an extension which is 0.1% of the original length?
40 N
50 N
100 N
200 N
The unit of strain ......
Dimensionless
kg/cm
N/m
kg/mm
Given the Young's modulus of elasticity below rank the metals according to the magnitude of tensile stress it can hold from highest to lowest.
Aluminum 69 GPa
Brass 125 GPa
Steel 200 GPa
Aluminum, Brass, Steel
Brass, Aluminum, Steel
Steel, Brass, Aluminum
A nylon string, has a diameter of 2mm, is pulled by a force of 100N. Determine the stress.
318 MPa
31.8 MPa
3.18 MPa
31.8 GPa
A concrete has a height and unit area of 5 m and 3 m2., respectively. If it supports a mass of 30,000 kg and its height changes by 0.025mm, what is its modulus of elasticity of this concrete?
2.00 GPa
19.6 GPa
2.00 MPa
19.6 MPa
The dimension of stress is same as that of:
Force
Pressure
Torque
Work
A wire is stretched to double its length. The strain is
Zero
1
2
0.5
If both the length and radius of the wire are doubled; how the modulus of elasticity change
Become one fourth
Halved
Doubled
Remain unchanged
Which letter is pointing to the elastic limit?
A
B
C
D
