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CBSE Questions for Class 11 Engineering Physics Mechanical Properties Of Solids Quiz 10 - MCQExams.com

A plank of mass M is suspended horizontally by using two wires as shown in the figure.They have same length (L) and same cross sectional area (A). Their Young's modulus are Y1 and Y2 respectively. The elastic potential energy of the system will be
1137846_9b553366363e45ee9a40795347e638b3.png
  • 2M2g2LA(Y1+Y2)
  • m2g2LA(Y1+Y2)
  • m2g2L2A(Y1+Y2)
  • M2g2L(Y1+Y2)2AY1Y2
To wires A and B have the same length and area of cross section. But Young's modulus of A is two times the Young's modulus of B. Then the ratio of force constant of A to that of B is
  • 1
  • 2
  • 12
  • 12 2
One end of uniform wire of length L and of weight W is attached  rigidly to a point in the roof and a weight  W_1   is suspended from its lower end. If s is the area of cross section of the wire, the stress in the wire at a height \dfrac{L}{4} from its lower end is -
  • \dfrac {W_1} {s}
  • \dfrac { \left[ { W }_{ 1 }+\dfrac { W }{ 4 } \right] }{ s }
  • \dfrac { \left[ { W }_{ 1 }+\dfrac { 3W }{ 4 } \right] }{ s }
  • \dfrac { { W }_{ 1 }+W }{ 4 }
When a metal wire is stretched by a load, the fractional change in its volume \Delta V/V is proportional to?
  • -\dfrac{\Delta l}{l}
  • \left(\dfrac{\Delta l}{l}\right)^2
  • \sqrt{\Delta l/l}
  • None of these
A metal rod of Young's modulus 2\times { 10 }^{ 10 }N{ m }^{ -2 } undergoes an elastic strain of 0.02%. The energy per unit volume stored in the rod, in Joules is ?
  • 400
  • 800
  • 1200
  • 1600
A wire elongates by l mm when a load W is hanged from it. If the wire goes over a pulley and two weights W each are hung at the two ends, the elongation of the wire will be (In mm) -
  • l
  • 2l
  • zero
  • \dfrac{l}{2}
Write Copper, Steel, Glass and Rubber in order of increasing coefficient of elasticity
  • Steel, Rubber, Copper, Glass
  • Rubber. Copper, Glass, Steel
  • Rubber. Glass, Steel, Copper
  • Rubber. Glass, Copper, Steel
A metal wire of length 2.5 m and area of cross section 1.5\times { 10 }^{ -6 }{ m }^{ -2 }, is stretched through 2 mm. Calculate the work done during stretching. Y=1.2\times { 10 }^{ 11 }N{ m }^{ -2 }
  • 0.15 J
  • 0.51 J
  • 1.51 J
  • 5.1 J
A mild steel wire of length 2L and cross-sectional area A is stretched, well within elastic limit, horizontally between two pillars. A mass m is suspended from the mind point of the wire. Strain in the wire is
  • \dfrac{x^{2}}{2L^{2}}
  • \dfrac{x}{L}
  • \dfrac{x^{2}}{L}
  • \dfrac{x^{2}}{2L}
A brass wire of diameter 1 mm and of length 2 m is stretched by applying a force of 20 N. If the increase in length is 0.51 mm. Then the Young's modulus of the wire is 
  • 8.848 \times 10^{10} N/m^2
  • 7.984 \times 10^{10} N/m^2
  • 6.984 \times 10^{10} N/m^2
  • 9.984 \times 10^{10} N/m^2
 A force of 15 N increases the length ofa by 1 \mathrm { mm }. The additional force require increase the length by 2.5 \mathrm { mm } in N is 
  • 2.25
  • 22.5
  • 37.5
  • 3.75
Ball A strikes with velocity u elastically with identical ball B at rest, inclined at an angle of with line joining the centers of two balls. What will be the speed of ball B after the collision: 
  • u
  • \dfrac{u\sqrt{3}}{2}
  • \dfrac{u}{2}
  • \dfrac{u}{\sqrt{2}}
A mass of 0.5\ kg is suspended from wire, then length of wire increase by 3\ mm then find out work done.
  • 4.5\times 10^{-3} J
  • 7.5\times 10^{-3} J
  • 9.3\times 10^{-2} J
  • 2.5\times 10^{-2} J
A material has poisson's ratio 0.3. If a uniform rod of it suffers a longitudinal strain of 25\times 10^{-3}, then the percentage increase in its volume is
  • 1\%
  • 2\%
  • 3\%
  • 4\%
If the interatomic spacing in a steel wire is 2.8\times 10^{-10}m and Y_{real}=2\times 10^{11}N/m^{2}, then force constant in N/m is -
  • 5.6
  • 56
  • 0.56
  • 560
The Young's modulus a rubber string 8 cm long and density 1.5 kg/ m^{3} is 5\times 10^{8}N/m^{2}, is suspended on the ceiling in a room. The increases in length due to its own weigth will be 
  • 9.6\times 10^{-5}m
  • 9.6\times 10^{-11}m
  • 9.6\times 10^{-3}m
  • 9.6 m
When a weight of 10 \,kg is suspended from a copper wire of length 3 \,m and diameter 0.4 \,mm. Its length increases by 2.4 \,cm. If the diameter of the wire is doubled, then the extension is its length will be :
  • 7.6 \,cm
  • 4.8 \,cm
  • 1.5 \,cm
  • 0.6 \,cm
The Poisson's ratio of the material of a wire is0.25 . If it is stretched by a force F, the longitudinal strain produced in the wire is 5 \times 10 ^ { - 4 } . What is the percentage increase in its volume?
  • 0.2
  • 2.5 \times 10 ^ { - 2 }
  • Zero
  • 1.25 \times 10 ^ { - 6 }
The length of a steel wire is l_{1} when the stretching force is T_{1} and l_{2} when the stretching force is T_{2} The natural length of the wire is 
  • \dfrac{l_{1}T_{1}+l_{2}T_{2}}{T_{1}+T_{2}}
  • \dfrac{l_{2}T_{1}+l_{2}T_{2}}{T_{1}+T_{2}}
  • \dfrac{l_{2}T_{1}+l_{2}T_{2}}{T_{1}-T_{2}}
  • \dfrac{l_{2}T_{1}-l_{1}T_{2}}{T_{1}-T_{2}}
Determine the pressure required to reduce the given volume of water by 2%. Bulk modulus of water is 2.2\times 10^{4}Nm^{-2}
  • 4.4\times 10^{7}Nm^{-2}
  • 2.2\times 10^{7}Nm^{-2}
  • 3.3\times 10^{7}Nm^{-2}
  • 1.1\times 10^{7}Nm^{-2}
A uniform cyclinder rod of length L, cross -sectional area A and youngs modules Y is acted upon by the forces shown in fig. The elongation of the rod is


1194886_17298b69fac2454a835442cd5be6536d.png
  • \dfrac{3FL}{5AY}
  • \dfrac{2FL}{5AY}
  • \dfrac{3FL}{8AY}
  • \dfrac{8FL}{3AY}
To apply a maximum stress of 1.2\times10^8N/m^2 under the action of force 40N the minimum radius of wire required is
  • 0.32mm
  • 0.66mm
  • 0.44mm
  • 0.22mm
When a mass of 8 kg is suspended from a string, its length is l_1. If a mass 10 kg is suspended, its length is l_2. Length, when a mass of 16 kg is suspended from it, is given by
  • 2l_2 - l_1
  • 2l_2 + l_1
  • 4l_2 + 3l_1
  • 4l_2 - 3l_1
A wire 2 m in length suspended vertically stretches by 10 mm when the mass of 10 kg is attached to the lower end. The elastic potential energy gain by the wire is?   (take g = 10 m/s^2)
  • 0.5 J
  • 5 J
  • 50 J
  • 500 J
One end of uniform wire of length L and of weight W is attached rigidly to a point in the roof and a weight W_{1} is suspended from its lower end. If s is the area of cross section of the wire, the stress in the wire at a height (3L/4) from its lower end is
  • \dfrac {W_{1}}{s}
  • \left [W_{1} + \dfrac {W}{4}\right ]s
  • \left [W_{1} + \dfrac {3W}{4}\right ]s
  • \dfrac {W_{1} + W}{s}
The isothermal Bulk modulus of an ideal gas at pressure 'P' is
1200453_ed26a70b940943bbb67c4f35111abc28.png
  • P
  • \gamma P
  • P/2
  • P/\gamma
What is the percentage increase in length of a wire of diameter 2.5 mm, stretched by a force of 100 kg wt? Young's modulus of elasticity of wire = 12.5 x 10^{11} dyne/cm^2  
  • 0.16%
  • 032%
  • 0.18%
  • 0.12%
A material has Poisson's ratio 0.5. If a uniform rod of it suffers a longitudinal strain of 3\times 10^{-3}, what will be percentage increase in volume?
  • 2\%
  • 3\%
  • 5\%
  • 0\%
A rod of length 3 in and uniform cross-section area 1mm^{2} is subjected by four forces at different cross section as shown in the figure. Yungs modulus of the rod is
1195658_95c6cf76acbc4ca3bebcee294793dd21.png
  • 5.235\ mJ
  • 7.25\ mJ
  • 3.6250\ mJ
  • 1.8125\ mJ
A rod of uniform cross sectional area A and length L has a weight W. It is suspended vertically from a fixed support vertically from a fixed support. If Young's modulus for rod is Y, then elongation produced in rod is
1206513_1de1c7c2e38a455bbc2a62c272006da2.png
  • \dfrac{WL}{YA}
  • \dfrac{WL}{2YA}
  • \dfrac{WL}{4YA}
  • \dfrac{3WL}{4YA}
Length of wire becomes 16 cm when certain tension is applied. If the tension is now doubled then wire is further elongated by 1 cm then original length of wire is
  • 14 cm
  • 15 cm
  • 15.5 cm
  • 16.5 cm
The bulk modulus of liquid  is 1.2\times10^9N/m^2 what is change in volume produced on a volume produced on a volume of 5 liters by a pressure equal to 10^6N/m^2?
  • 1.2cc
  • 3.2cc
  • 4.2cc
  • 5cc
If the interatomic spacing in a steel wire is { 2.8\times 10 }^{ -10 } m. and { Y }_{ steal }=2\times 10^{ 11 }N/m^{ 2 },then force constant in N/m is-
  • 5.6
  • 56
  • 0.56
  • 560
A brass bar, having cross sectional area 10 cm^2 is subjected to axial forces as shown in figure. Total elongation of the bar is (Take Y = 8 \times 10^2 \ t/m^2).
1202806_629931b2f44e406e821dda7ac4483b98.png
  • 0.0775\ cm
  • 7.5\ cm
  • 0.75\ cm
  • 0.075\ cm
In a Young's double slit experiment, the intensity at the cetral maximum is l_{0-}. The intensity ata distance \beta/4 from the central maximum is (\beta is frige width)
  • l_0
  • \dfrac{l_0}{2}
  • \dfrac{l_0}{\sqrt2}
  • \dfrac{l_0}{4}
In Searle's apparatus we have two wires. During experiment we study the extension in one wire. The use of second wire is-
  • to support the apparatus because it is heavy and may not break single wire
  • to compensate the changes in length caused by changes in temperature of atmosphere during experimentation
  • to keep the apparatus in level so that extension is measured accurately
  • all the three above
The Young's modulus of a rubber string 8 cm long and density 1.5 kg/m^{3} is 5\times 10^{8} N/m^{2}, is suspended on the ceiling in a room. The increase in length due to its own weight will be:-
  • 9.6\times 10^{-5}m
  • 9.6\times 10^{-11}m
  • 9.6\times 10^{-3}m
  • 9.6 m
In a  young's double-slit experiment, the slits are separated by 0.5 mm, and the screen is placed 150 cm away. A beam of light consisting of two wavelengths, 650 nm, and 520 nm, is used to obtain interference fringes on the screen. The least distance from the common central maxima to the point where the bright fringes due to both the wavelengths coincide is:  
  • 9.75 mm
  • 15.6 mm
  • 1.56 mm
  • 7.8mm
An iron wore and copper wire having same length and cross-section are suspended from same roof Young's modulus of copper is \dfrac 13 that of iron. Then the ratio of the weights to be added at their ends so that their ends are at the same level is
  • 1:3
  • 1:9
  • 3:1
  • 9:1
If the work done in stretching a wire by 1\ mm is 2\ J, then work necessary for stretching another wire of same material but with double radius of cross-section and half of the length by 1\ mm is 
  • 8\ J
  • 16\ J
  • 4\ J
  • 32\ J
A body of mass 1 Kg is fastended to one end of a steel wire of cross - sectional area 3\times 10^{-6} m^{2} and it rotated in horizontal circle of radius 20 cm with a constant speed of 2 m/s .The elongation in the wire is (Y = 2\times 10^{11}N / m^{2})
  • 0 . 33\times 10^{-5} m
  • 0 . 67 \times 10^{-5} m
  • 2 \times 10^{-5} m
  • 4\times10^{-5} m
A steel wire (original length = 2m, diameter = 1mm) and a copper wire ( original length =1m, diameter =2mm) are loaded as shown in  the figure . Find the ratio of extension of steel wire to that of copper wire. Given , Young's modulus of steel = 2\times  10^{11} Nm^{-2} and that of copper is   10^{11} Nm^{-2}.
1224019_0789a139d029400485e042c13f77d740.png
  • \frac{10}{3}
  • 5
  • \frac{20}{3}
  • \frac{14}{3}
An elongation of 0.1^\circ in a wire of cross sectional area 10^{-6}m^{2} causes a tension of 100n. The Young's modulus is-
  • 10^{12}N/M^{2}
  • 10^{11}N/M^{2}
  • 10^{10}N/M^{2}
  • 10^{2}N/M^{2}
A material has poisson's ratio 0.If a uniform rod of it suffers a longitudinal strain of 2\times { 10 }^{ -3 } then the percentage increase in its volume is 
  • 0%
  • 10%
  • 20%
  • 5%
A man grows into a giant such that his linear dimensions increase by  a factor of 9. Assuming that his density remains same, the stress in the leg will change by a factor of?
  • 81
  • \cfrac{1}{81}
  • 9
  • \cfrac{1}{9}
The Young's modulus of the material of a rod is 20 \times 10^{10} pascal. When the longitudinal strain is 0.04%, The energy stored per unit volume is
  • 4 \times 10^{3} \ J/m^3
  • 8 \times 10^{-3} \ J/m^3
  • 16 \times 10^{-3} \ J/m^3
  • 16 \times 10^{3} \ J/m^3
A woman with a mass of 65\ kg puts all her weight on one heel of her high-heel shoe. The cross-sectional area of the heel is 1\ cm^{2}. According to the table, if she is standing on a pane of glass that is flat against the ground, does the glass break :
  • No, because the stress is less than the ratio for the ultimate strength to Young's modulus for glass
  • No, because the stress is less than the ultimate strength of glass
  • Yes, because the stress is greater than the ratio for the ultimate strength to Young's modulus for glass
  • No, because the stress is greater than the ultimate strength of glass
A force F doubles the length of wire of cross-section a. The Young modulus of wire is
  • \dfrac{F}{a}
  • \dfrac{F}{3a}
  • \dfrac{F}{2a}
  • \dfrac{F}{4a}
A metal wire of length 1\ m and cross-section area 2\ mm^{2} and Young's modulus of elasticity Y=4\times 10^{11}\ N/m^{2} is stretched by 2\ mm. Then
  • the restoring force developed in the wire is 1600\ N
  • the energy density in the wire is 4\times 10^{5}\ J/m^{3}
  • the restoring force developed in the wire is 400\ N
  • the total elastic energy stored in the wire is 1.6\ J
An elastic metal rod will change its length when it
  • falls vertically under its weight
  • is pulled along its lengthy by a force acting at one end
  • both
  • none
0:0:1


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