WorksheetsY 12 Materials Young Modulus
Total questions: 27
Worksheet time: 27mins
A steel wire W has a length l and a circular cross-section of radius r. When W hangs vertically and a load is attached to the bottom end, it extends by e.
Another wire X made from the same material has the same load attached to it.
Which length and radius for X will produce an extension of e/4 ?
A
B
C
D
What cannot be used as a unit for the Young modulus?
N m–2
Pa
kg m–2 s–2
kg m–1 s–2
Two separate wires X and Y have the same original length and cross-sectional area.
The graph shows the extension ∆L produced in X and Y when the tensile force F applied to the wires is increased up to the point where they break.
Which statement is incorrect?
For a given extension more energy is stored in X than in Y.
The Young modulus of the material of wire Y is greater than that of wire X.
Both wire X and wire Y obey Hooke’s law.
Wire X has a greater breaking stress than wire Y.
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 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 brass wire has reached its elastic limit. It means that
if any further stress is applied, the wire will break.
if any further stress is applied, the deformation of the wire will not be reversible.
the deformation no longer obeys Hooke's law
the wire will continue deforming with no additional stress.
Figure below shows a stress-stain graph for a ductile metal under tension. Which part represents the plastic deformation?
P → Q
Q → R
R → T
R → U
The cause of elasticity of a substance is
deformation
large internal restoring force
low internal restoring force
less distance between the molecules
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 moduli 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 a wire breaks just after plastic flow begins then material is
strong
hard
brittle
ductile
A cylindrical rod of cross-sectional area A experienced pressure p due to a compressive force F. If the force applied is reduced to one-third what happens to pressure?
also reduced to one-third
tripled
remains the same
What is the correct label for A and B shown in the figure below?
A - Tension; B- Compression
A - Compression; B - Tension
A - Torsion; B - Tension
A nylon string, has a diameter of 2mm, is pulled by a force of 100N. Determine the stress.
315 MPa
31.5 MPa
3.15 MPa
How is stress calculated?
Number of sleepless nights divided by number of cups of coffee
Divide load (F) by the original test sample cross-sectional area (A0).
Elongation (δ) under load divided by the original Length (L0)
Stress (σ) divided by strain (ε)
Material failure with little or no ductility.
Brittleness
Toughness
Ductility
Plasticity
Hooke's law states that
the extension is proportional to the load when the elastic limit is not exceeded
the extension is inversely proportional to the load when the elastic limit is not exceeded
the extension is independent of the load when the elastic limit is not exceeded
load is dependent on extension
At ‘yield point’ of a copper wire
the load hasn't exceeded the elastic limit yet; so, Hooke's law applies
the load has already exceeded the elastic limit and the material has become plastic
even the plastic stage has passed and the wire has snapped already
Like Brass and Bronze, Copper has no yield point
If the length of wire is stretched by a load is doubled, then it's Young's modulus will be
doubled
halved
becomes four times
unaffected
Substances that elongate considerably and undergo plastic deformation before they break are known as
brittle material
ductile material
stiff material
plastic material
Copper has been used in electrical wiring since the invention of the electromagnet and the telegraph in the 1820's. What property of solid best describe this material?
Porosity
Malleabilty
Brittleness
Ductility
What is the correct formula for Young Modulus
Y=AeFl
F=leYA
l=AF
Y=ϵσ
