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Page 1
Mechanical Properties of Solids
Multiple Choice Questions – I
1. Modulus of rigidity of ideal liquids is
(a) infinity.
(b) zero.
(c) unity.
(d) some finite small non-zero constant value.
Ans: Correct option (b)
Because since we know from given condition that liquid is ideal, thus it does not
have frictional force among its layers. Hence, tangential forces are zero since no
stress is developed there.
2. The maximum load a wire can withstand without breaking when its length
is reduced to half of its original length, will
(a) be double.
(b) be half.
(c) be four times.
(d) remain same.
Ans: Correct option (d)
Because Breaking stress
Breaking force
=
Area of crosss ection
Page 2
Mechanical Properties of Solids
Multiple Choice Questions – I
1. Modulus of rigidity of ideal liquids is
(a) infinity.
(b) zero.
(c) unity.
(d) some finite small non-zero constant value.
Ans: Correct option (b)
Because since we know from given condition that liquid is ideal, thus it does not
have frictional force among its layers. Hence, tangential forces are zero since no
stress is developed there.
2. The maximum load a wire can withstand without breaking when its length
is reduced to half of its original length, will
(a) be double.
(b) be half.
(c) be four times.
(d) remain same.
Ans: Correct option (d)
Because Breaking stress
Breaking force
=
Area of crosss ection
As breaking force does not depend on length. Thus, changing the cross section has
no effect which implies breaking force remain same.
3. The temperature of a wire is doubled. The Young's modulus of elasticity
(a) will also double.
(b) will become four times.
(c) will remain same.
(d) will decrease.
Ans: Correct option (d)
Because as we know that
t0
L = L (1 + a ) t ?
t 0 0
L - L = a L Lt ? ? ?
00
stress FL FL
Y = = =
strain A A(1 + a ) Lt ??
1
Y
t
?
?
Thus, when temperature increases then Young’s modules decreases.
4. A spring is stretched by applying a load to its free end. The strain produced
in the spring is
(a) volumetric.
(b) shear.
(c) longitudinal and shear.
(d) longitudinal.
Page 3
Mechanical Properties of Solids
Multiple Choice Questions – I
1. Modulus of rigidity of ideal liquids is
(a) infinity.
(b) zero.
(c) unity.
(d) some finite small non-zero constant value.
Ans: Correct option (b)
Because since we know from given condition that liquid is ideal, thus it does not
have frictional force among its layers. Hence, tangential forces are zero since no
stress is developed there.
2. The maximum load a wire can withstand without breaking when its length
is reduced to half of its original length, will
(a) be double.
(b) be half.
(c) be four times.
(d) remain same.
Ans: Correct option (d)
Because Breaking stress
Breaking force
=
Area of crosss ection
As breaking force does not depend on length. Thus, changing the cross section has
no effect which implies breaking force remain same.
3. The temperature of a wire is doubled. The Young's modulus of elasticity
(a) will also double.
(b) will become four times.
(c) will remain same.
(d) will decrease.
Ans: Correct option (d)
Because as we know that
t0
L = L (1 + a ) t ?
t 0 0
L - L = a L Lt ? ? ?
00
stress FL FL
Y = = =
strain A A(1 + a ) Lt ??
1
Y
t
?
?
Thus, when temperature increases then Young’s modules decreases.
4. A spring is stretched by applying a load to its free end. The strain produced
in the spring is
(a) volumetric.
(b) shear.
(c) longitudinal and shear.
(d) longitudinal.
Ans: Correct option is (c) because when spring is stretched by load then its shape
and length changes which produces shearing and longitudinal strain.
5. A rigid bar of mass M is supported symmetrically by three wires each of
length 1. Those at each end are of copper and the middle one is of iron. The
ratio of their diameters, if each is to have the same tension, is equal to
(a)
copper
iron
Y
Y
(b)
iron
copper
Y
Y
(c)
2
iron
2
copper
Y
Y
(d)
iron
copper
Y
Y
Ans: Correct option is (b)
Because
2
Stress FL FL
Y = = =
Strain A
D
p
2
L
L
?
??
?
??
??
2
4FL
Y =
p D L ?
L = l
Copper iron( ) L L g ? ? ?
F = weight of rod same in both cases
Page 4
Mechanical Properties of Solids
Multiple Choice Questions – I
1. Modulus of rigidity of ideal liquids is
(a) infinity.
(b) zero.
(c) unity.
(d) some finite small non-zero constant value.
Ans: Correct option (b)
Because since we know from given condition that liquid is ideal, thus it does not
have frictional force among its layers. Hence, tangential forces are zero since no
stress is developed there.
2. The maximum load a wire can withstand without breaking when its length
is reduced to half of its original length, will
(a) be double.
(b) be half.
(c) be four times.
(d) remain same.
Ans: Correct option (d)
Because Breaking stress
Breaking force
=
Area of crosss ection
As breaking force does not depend on length. Thus, changing the cross section has
no effect which implies breaking force remain same.
3. The temperature of a wire is doubled. The Young's modulus of elasticity
(a) will also double.
(b) will become four times.
(c) will remain same.
(d) will decrease.
Ans: Correct option (d)
Because as we know that
t0
L = L (1 + a ) t ?
t 0 0
L - L = a L Lt ? ? ?
00
stress FL FL
Y = = =
strain A A(1 + a ) Lt ??
1
Y
t
?
?
Thus, when temperature increases then Young’s modules decreases.
4. A spring is stretched by applying a load to its free end. The strain produced
in the spring is
(a) volumetric.
(b) shear.
(c) longitudinal and shear.
(d) longitudinal.
Ans: Correct option is (c) because when spring is stretched by load then its shape
and length changes which produces shearing and longitudinal strain.
5. A rigid bar of mass M is supported symmetrically by three wires each of
length 1. Those at each end are of copper and the middle one is of iron. The
ratio of their diameters, if each is to have the same tension, is equal to
(a)
copper
iron
Y
Y
(b)
iron
copper
Y
Y
(c)
2
iron
2
copper
Y
Y
(d)
iron
copper
Y
Y
Ans: Correct option is (b)
Because
2
Stress FL FL
Y = = =
Strain A
D
p
2
L
L
?
??
?
??
??
2
4FL
Y =
p D L ?
L = l
Copper iron( ) L L g ? ? ?
F = weight of rod same in both cases
2
1
Y
D
?
2
11
D , D
YY
??
copper
iron
iron copper
D
Y
=
DY
6. A mild steel wire of length 2L and cross-sectional area A is stretched, well
within elastic limit, horizontally between two pillars (Figure). A mass m is
suspended from the mid-point of the wire. Strain in the wire is
(a)
2
2
x
2l
(b)
l
x
Page 5
Mechanical Properties of Solids
Multiple Choice Questions – I
1. Modulus of rigidity of ideal liquids is
(a) infinity.
(b) zero.
(c) unity.
(d) some finite small non-zero constant value.
Ans: Correct option (b)
Because since we know from given condition that liquid is ideal, thus it does not
have frictional force among its layers. Hence, tangential forces are zero since no
stress is developed there.
2. The maximum load a wire can withstand without breaking when its length
is reduced to half of its original length, will
(a) be double.
(b) be half.
(c) be four times.
(d) remain same.
Ans: Correct option (d)
Because Breaking stress
Breaking force
=
Area of crosss ection
As breaking force does not depend on length. Thus, changing the cross section has
no effect which implies breaking force remain same.
3. The temperature of a wire is doubled. The Young's modulus of elasticity
(a) will also double.
(b) will become four times.
(c) will remain same.
(d) will decrease.
Ans: Correct option (d)
Because as we know that
t0
L = L (1 + a ) t ?
t 0 0
L - L = a L Lt ? ? ?
00
stress FL FL
Y = = =
strain A A(1 + a ) Lt ??
1
Y
t
?
?
Thus, when temperature increases then Young’s modules decreases.
4. A spring is stretched by applying a load to its free end. The strain produced
in the spring is
(a) volumetric.
(b) shear.
(c) longitudinal and shear.
(d) longitudinal.
Ans: Correct option is (c) because when spring is stretched by load then its shape
and length changes which produces shearing and longitudinal strain.
5. A rigid bar of mass M is supported symmetrically by three wires each of
length 1. Those at each end are of copper and the middle one is of iron. The
ratio of their diameters, if each is to have the same tension, is equal to
(a)
copper
iron
Y
Y
(b)
iron
copper
Y
Y
(c)
2
iron
2
copper
Y
Y
(d)
iron
copper
Y
Y
Ans: Correct option is (b)
Because
2
Stress FL FL
Y = = =
Strain A
D
p
2
L
L
?
??
?
??
??
2
4FL
Y =
p D L ?
L = l
Copper iron( ) L L g ? ? ?
F = weight of rod same in both cases
2
1
Y
D
?
2
11
D , D
YY
??
copper
iron
iron copper
D
Y
=
DY
6. A mild steel wire of length 2L and cross-sectional area A is stretched, well
within elastic limit, horizontally between two pillars (Figure). A mass m is
suspended from the mid-point of the wire. Strain in the wire is
(a)
2
2
x
2l
(b)
l
x
(c)
2
x
l
(d)
2
x
2l
Ans: Correct option is (a) because
l (AO BO) AB ? ? ? ?
l 2AO 2I 2[AO l] ? ? ? ? ?
? ?
1
22
2
2 l x 1
??
? ? ?
??
??
1
2
2
2
x
21 1 1
l
??
??
??
? ? ?
??
??
??
??
2 2 2
22
2 1 1 2
22
x x x
ll
l l l
??
? ? ? ? ? ?
??
??
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