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 $$Y_1$$ and $$Y_2$$ respectively. The elastic potential energy of the system will be
1137846_9b553366363e45ee9a40795347e638b3.png
  • $$\dfrac{2M^2g^2L}{A(Y_1+Y_2)}$$
  • $$\dfrac{m^2g^2L}{A(Y_1+Y_2)}$$
  • $$\dfrac{m^2g^2L}{2A(Y_1+Y_2)}$$
  • $$\dfrac{M^2g^2L(Y_1+Y_2)}{2AY_1Y_2}$$
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
  • $$1$$
  • $$2$$
  • $$\dfrac{1}{2}$$
  • $$12\ 2$$
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 is$$0.25 .$$ 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
  • $$0.32$$mm
  • $$0.66$$mm
  • $$0.44$$mm
  • $$0.22$$mm
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 $$10^6N/m^2$$?
  • $$1.2$$cc
  • $$3.2$$cc
  • $$4.2$$cc
  • $$5$$cc
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


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Class 11 Engineering Physics Quiz Questions and Answers