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

If the speed of longitudinal wave equals $$10$$ times the speed of the transverse waves in a stretched wire of material which has modulus of elasticity E, then the stress in the wire is
  • $$100E$$
  • $$\dfrac {E}{ 100 } $$
  • $$\dfrac {E}{ 10 } $$
  • $$10E$$
Two wires of the same material have masses in the ratio 3:The ratio of their extensions under the same load if their lengths are in the ratio 9:10 is
  • 5 : 3
  • 27 : 40
  • 6 : 5
  • 27 : 25
A $$40\ cm$$ wire having a mass $$3.2\ gm$$ and area of cross-section $$1\ mm^{2}$$ is stretched between two supports $$40.05\ cm$$ apart. In its fundamental note, the wire vibrates with a frequency $$220\ Hz$$. The Young's molulus is :
  • $$1.98\times 10^{11}\ N/m^{2}$$
  • $$2.2\times 10^{11}\ N/m^{2}$$
  • $$3.96\times 10^{11}\ N/m^{2}$$
  • $$3.2\times 10^{11}\ N/m^{2}$$
The extension produced in a wire by the application of a load is $$3.0$$ mm. The extension produced in a wire of the same material and length but half the radius by the same load is:
  • $$5$$ mm
  • $$9$$ mm
  • $$12$$ mm
  • $$13$$ mm
The $$'\sigma '$$ of a material is 0.If a longitudinal strain of $$4.0\times { 10 }^{ -3 }$$ is caused, by what percentage will the volume change -
  • 0.48 %
  • 0.32 %
  • 0.24 %
  • 0.50 %
The force required to punch a square hole 2 cm side in steel sheet 2 mm thick is:-
(shearing stress of steel sheet $$=3.5 \times10^8 N/m^2)$$
  • $$5.6\times10^4 N$$
  • $$3.4\times10^4 N$$
  • $$9.1\times10^4 N$$
  • $$6.8\times10^4 N$$
In case of bending of a beam, depression $$\delta$$ depends on Young modulus of elasticity $$Y$$ as
  • $$\propto Y$$
  • $$\propto Y^{2}$$
  • $$\propto Y^{-1}$$
  • $$\propto Y^{-2}$$
When a wire is stretched, an amount of work is done. What is the amount of work done in stretching a wire through $$0.1mm$$, if its length is $$2m$$ and area of cross - section, $$10^-6m^2 ( Y=2 \times10^11 N/m^2)$$
  • $$5 \times 10^-1 J$$
  • $$5 \times 10^-2 $$
  • $$5 \times 10^-3 J $$
  • $$ 5 \times 10^-4 J $$
On suspending a weight $$Mg$$, the length $$l$$ of elastic wire and area of cross-section $$A$$ its length becomes double the initial length. the instantaneous stress action on the wire is
  • $$Mg/A$$
  • $$Mg/2A$$
  • $$2Mg/A$$
  • $$4Mg/A$$
A bar is subjected to an axial forces as shown in figure. Find the total elongation in the bar. (E is the modulus of elasticity of the bar and A is its cross-section)
1278350_bc14dab9962442dcb3a33e9ff9e01537.png
  • $$\dfrac{FI}{AE}$$
  • $$\dfrac{2FI}{AE}$$
  • $$\dfrac{3FI}{AE}$$
  • $$\dfrac{4FI}{AE}$$
When a weight of 10 kg is suspended from a copper wire of length 3 meters and diameter 0.4 mm, its length increases by 2.4 cm. If the diameter of the wire is doubled, then the extension in its length will be-
  • 9.6 cm
  • 4.8 cm
  • 1.2 cm
  • 0.6 cm
A wire is subjected to a tensile stress. If A represents area of cross-section, L represents original length, I represents extension and Y is Young's modulus of elasticity, then elastic potential energy of the stretched wire is
  • $$U=\frac{2L}{AY} I^2$$
  • $$U=\frac{AL}{2Y} I^2$$
  • $$U=\frac{AY}{2L} I^2$$
  • $$U=\frac{1}{4} \frac{AY}{L} I^2$$
A square frame of ABCD consisting of five steel bars of cross section area $$400 \,mm^2$$ and joined by pivot is subjected to action of two forces $$P =40 \, kN$$ in the direction of the diagonal as shown.Find change in angle at $$A$$ if Young's modulus $$Y=2\times 10^5 \,N/min.$$
1289747_213c2ac74d2e4712a3ca815b11769c70.png
  • $$\dfrac{1}{2000}$$rad
  • $$\dfrac{1}{1000}$$rad
  • $$\dfrac{\sqrt{2}}{1000}$$rad
  • $$\dfrac{\sqrt{3}}{1000}$$rad
The strain produced in the wire of length 60 cm is 1%, the change in the length of wire is
  • 0.6 cm
  • 6 cm
  • 60 cm
  • 0.016 cm
For maximum extension with given load for a wire with same value of Young's modulus of elasticity, which is true?
  • $$l=300 cm, d= 10 cm$$
  • $$l=200 cm, d=5 cm$$
  • $$l=100 cm, d=2 cm$$
  • $$l=50 cm, d=0.5 cm$$

A steel bar of cross-section $$500$$ mm and length $$1$$ m acted upon by two forces as shown If Young modulus of elasticity of steel is $$200 \times 10^9$$ $$N/m^2$$ then elongation of the rod is 


1311217_8321896861be43d798700abe2ec8819c.png
  • $$0.05$$ mm
  • $$0.5$$ mm
  • $$0.1$$ mm
  • $$0.2$$ mm
A wire of density $$ 9 \times 10^3 Kg/m^3 $$ is stretched between two clamps 1 m apart and is stretched to an extension of $$ 4.9 \times 10^{-4} $$ meter, Young's modulus of material is $$ 9 \times 10^{10} N/m^2 $$. Then 
  • The lowest frequency of standing waveis 35 Hz
  • The frequency of 1 st overtone is 70 Hz
  • The frequency of 1 st overtone iis 105 Hz
  • A and B both
A metal wire having Poisson's ratio $$\frac {  1}{ 4 }$$ Young's modulud $$8\times {10  }^{  10} N/m^2$$ is stretched force, which produces a lateral strain of 0.02 it. The elastic potential energy stored per volume in wire is$$[in J/m^3]$$
  • $$2.56\times 10^4$$
  • $$1.78\times 10^2$$
  • $$3.72\times 10^2$$
  • $$3.18\times 10^5$$
The bulk modulus of gas is $$6 \times 10^3N/m^2$$. The additional pressure needed to reduce the volume of liquid by 10% is
  • $$1200 N/m^2$$
  • $$600 N/m^2$$
  • $$2400 N/m^2$$
  • $$1600 N/m^2$$
A wire is stretched under a force. If the wire suddenly snaps, the temperature of the wire
  • Remains the same
  • Decreases
  • Increases
  • First decreases then increases
The bulk modulus of a spherical object is B. If it is subjected to uniform pressure p, the fractional decrease in radius is
  • $$\frac{p}{B}$$
  • $$\frac{B}{3p}$$
  • $$\frac{3p}{B}$$
  • $$\frac{p}{3B}$$
When a rubber cord is stretched, the change in volume with respect to change in its linear dimensions is negligible. The Poisson's ratio for rubber is 
  • 1
  • 0.25
  • 0.5
  • 0.75
The maximum intensity of fringes in Young's experiment is l. If one of the slits is closed , then intensity at that place becomes $${ I }_{ 0 }$$. then relation between I and $${ I }_{ 0 }$$ is
  • $$I={ I }_{ 0 }$$
  • $$I=2{ I }_{ 0 }$$
  • $$I=4{ I }_{ 0 }$$
  • there is no relation between $$I$$ and $$I_0$$
When the load on a wire is increased from $$3 \mathrm { kg }-wt$$ to $$8\mathrm { kg } -wt$$, the elongation increases from $$0.61 \mathrm { mm }$$to $$1.02 \mathrm { mm } $$ . The required work done during the extension of the wire, is
  • $$16 \times 10 ^ { - 3 } \mathrm { J }$$
  • $$8 \times 10 ^ { - 2 } \mathrm { J }$$
  • $$20 \times 10 ^ { - 2 } \mathrm { J }$$
  • $$31 \times 10 ^ { - 3 } \mathrm { J }$$
A copper wire and a steel wire of the same diameter and length 1 m and 2 m respectively are connected end and a force is applied which stretches their combined length by 1 cm. How much each wire is elongated respectively. Y of copper = $$1.2\times { 10 }^{ 10 }$$ $$M{ m }^{ -2 }$$ and Y of steel +$$2.0\times { 10 }^{ 10 }\quad N{ m }^{ -2 }$$
  • 0.45 cm, 0.55 cm
  • 0.55 cm, 0.45 cm
  • 0.045 cm , 0.55 cm
  • 0.45 cm, 0.055 cm
 When a pressure of $$100$$ atmosphere is applied on a spherical ball of rubber, then its volume reduces to $$0.01 \%$$ . The bulk modulus of the material of the rubber in dyne $$\mathrm { cm } ^ { - 2 }$$ is
  • $$10 \times 10 ^ { 12 }$$
  • $$100 \times 10 ^ { 12 }$$
  • $$1 \times 10 ^ { 12 }$$
  • $$20 \times 10 ^ { 12 }$$
If rigidity modulus is 2.6 times of youngs modulus then the value of poission's ratio is 
  • 0.2
  • 0.3
  • 0.5
  • 0.1
A steel wire of mass 3.16 Kg is stretched to a tensile strain of 1 x$${ 10 }^{ -3 }$$. What is the elastic deformation energy if density p=7.9g/cc and Y=2x$$10^{ 11 }N/m^{ 2 }$$
  • 4 KJ
  • 0.4 KJ
  • 0.04 KJ
  • 40 J
Find the intensity on the screen at $$O$$ if only $$S_{3}$$ is covered 
  • $$\dfrac {\sqrt {3}I_{o}}{7}$$
  • $$\dfrac {\sqrt {3}I_{o}}{\sqrt {7}}$$
  • $$\dfrac {3I_{2}}{7}$$
  • $$\dfrac {I_{o}}{2}$$
A 2.0 m long steel cable has cross-sectional area of $$ 0.30 cm^2 $$. A 550 kg load is now hung from the cable. Assume that the cable behaves like a solid rod with an uniform cross-sectional area. Then the stress of the cable is:
  • $$1.8 \times 10^8 Pa$$
  • $$2.8 \times 10^8 Pa$$
  • $$18 \times 10^8 Pa$$
  • $$28 \times 10^8 Pa$$
Two wires of length $$l$$, radius $$r$$ and length $$2l$$, radius $$2r$$ having same Young's modulus $$Y$$ are hung with weight $$mg$$. Net elongation is
  • $$3\ mgl/2\pi r^{2}Y$$
  • $$1\ mgl/2\pi r^{2}Y$$
  • $$2\ mgl/3\pi r^{2}Y$$
  • $$3\ mgl/3\pi r^{2}Y$$
The time after which the block reaches the position where is laming maximum elongation is
  • $$2\pi \sqrt { \dfrac { m }{ k } } $$
  • $$\pi \sqrt { \dfrac { m }{ k } } $$
  • $$\frac { \pi }{ 2 } \sqrt { \dfrac { m }{ k } } $$
  • $$\pi \sqrt { \dfrac { m }{ 2k } } $$
All three sliits are now uncovered  and a transparent plate of thickness $$1.4\ \mu$$ and refreactive index $$1.25$$ is placecd  in front of $$S_{2}$$. Rresultant intensity at point $$O$$ is
  • $$3I_{0}/7$$
  • $$4I_{0}/7$$
  • $$5I_{0}/7$$
  • $$6I_{0}/7$$
Find the intensity on the screen at $$O$$ if $$S_{1}$$ and $$S_{3}$$ are covered.
  • $$\dfrac {I_{0}}{\sqrt {7}}$$
  • $$\dfrac {I_{0}}{{7}}$$
  • $$\dfrac {I_{0}}{\sqrt {6}}$$
  • $$\dfrac {I_{0}}{{6}}$$
A metallic beam having Young's modulus $$Y$$ is supported at the two ends. It is loaded at the centre. The depression of the centre is proportional to
  • $$Y$$
  • $$1/Y$$
  • $$Y^{2}$$
  • $$1/Y^{2}$$
What happens when the applied load increases and upto breaking stress in the experiment to determine the Young's modulus of elasticity?
  • The area of wire goes in decreasing and wire extends and breaks.
  • The area of wire goes in increasing and wire breaks.
  • The wire extends and area remains constant.
  • The area remains same and wire length is also same.
Calculate the speed of sound in oxygen at $$0^{\circ}C$$ and 1 atm. (Bulk modulus of elasticity of $$O_{2}$$ is $$1.41\times 10^{5}$$ Pa and density is 1.43 kg/$$m^{3}$$)
  • 300 m/s
  • 340 m/s
  • 314 m/s
  • none of these
Which of the following substances has the highest value of the young's modulus?
  • Steel
  • Rubber
  • wood
  • Plastic
The isothermal bulk modulus of a gas at atmospheric pressure is
  • 1 mm of Hg
  • 13.6 mm of Hg
  • $$1.013\times { 10 }^{ 5 }N/{ m }^{ 2 }$$
  • none of these
A wire of mass $$M ,$$ density $$\rho$$ and radius $$R$$ is stretched. If $$r$$ is the change in the radius and $$l$$ is the change in its length, then Poisson's ratio is given by :
  • $$\dfrac { \pi l } { \rho M r R ^ { 3 } }$$
  • $$\dfrac { R M \pi } { l \rho r ^ { 3 } }$$
  • $$\dfrac { r M } { \pi l \rho R ^ { 3 } }$$
  • $$\dfrac { l M } { \pi l \rho R ^ { 3 } }$$
Two wires of equal length and cross-section area suspended as shown in figure. Their Young's modulus are$$Y_1$$ and $$Y_2$$ respectively. The equivalent Young's modulus will be
1422549_a6d985a9ebd045e9b3919e31606f66a9.png
  • $$Y_1 + Y_2$$
  • $$\dfrac{Y_1 + Y_2}{2}$$
  • $$\dfrac{Y_1Y_2}{Y_1 + Y_2}$$
  • $$\sqrt{Y_1Y_2}$$
A thin ring of radius R is made up of a material of density $$\rho $$ and young's modulus Y. If the ring is rotated about its centre in its own plane with an angular velocity $$\omega $$ then the small increase in radius $$(\Delta R)$$ of the ring  is
  • $$\cfrac { \rho { \omega }^{ 2 }{ R }^{ 3 } }{ Y } $$
  • $$\cfrac{\rho\omega^2}{YR^3}$$
  • $$\cfrac{Y}{\rho\omega^2R^3}$$
  • None
The Young's modulus of a wire is numerically equal to the stress which will
  • not charge the length of the wire
  • double the length of the wire
  • increase the length by 50%
  • charge the radius of the wire to half
The SI unit of stress is same as the SI unit of 
  • Strain
  • Modulus of elasticity
  • Pressure
  • Both (2) and (3)
A 1000 kg lift is tied with metallic wires of maximum safe stress of $$1.4 \times 10^8 N/m^2$$. If the maximum acceleration of the lift is $$1.2 cm^{-2}$$, then the minimum diameter of the wire is 
  • $$0.01 m$$
  • $$0.01 cm$$
  • $$0.001 m$$
  • $$ 0.02 cm$$
Two wires of different material and radius have their length in ratio of $$1:2.$$ if these were stretched by the same force$$,$$ the strain produced will be in the ratio$$.$$  
  • $$4 : 1$$
  • $$1 : 1$$
  • $$2 : 1$$
  • $$1 : 2$$
The bulk modulus of elasticity for a monoatomic ideal gas during an isothermal process is (P = pressure of the gas) 
  • $$P$$
  • $$\dfrac{2P}3$$
  • $$\dfrac{5P}{3}$$
  • $$\dfrac{7P}{5}$$
Statement I:- Bulk modulus of an ideal fluid is infinite.
Statement II:- An ideal fluid is compressible.
  • Statement I is true,statement II is true and statement II is a correct explanation for statement I.
  • Statement I is true,statement IIis true and statement II is NOT the correct explanation for statement I.
  • Statement I is true, statement II is false.
  • Statement I is false,statement II is true.
A telephone wire between the two poles is 50 m long and 1 mm in radius.When it is stretched by a load of 65 kg,its length becomes 50.12 m.Calculate Young's modulus of elasticity.
  • $$4.22\times10^{10} Nm^{-2}$$
  • $$8.44\times10^{10} Nm^{-2}$$
  • $$4.22\times10^{9} Nm^{-2}$$
  • $$8.44\times10^{9} Nm^{-2}$$
Pick up the correct statement:
  • Cubic crystals exhibit isotropic nature with respect to therma expansion
  • Anisotropic solids expand in one direction and contract in perpendicular direction
  • Many of the crystals are anisotropic solids
  • Rock salt crystal exhibits isotropic nature with respect to thermal expansion
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