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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
Write Copper , Steel , Glas and Rubber in order at increasing coefficient of elasticityA. Steel, Rubber, Copper, GlassB. Rubber, Copper, Glass, SteelC. Rubber , Glass , Steel, CopperD. Rubber , Glass , Copper, Steel |
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Answer» Correct Answer - D (d) Rubber `lt` Glass `lt` Copper `lt` Steel |
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| 152. |
Statement-1: The bridges are declared unsafe after a long use. Statement-2: Elastic strength of bridges losses with time.A. Statement-1, is true, Statement-2 is true, Statement-2 is correct explanation for statement-1B. Statement-1 is true, statement-2 is true, statement-2 is NOT a correct explantion for statement-1C. statement-1 is true, statement-2 is falseD. statement-1 is false statement-2 is true |
| Answer» Correct Answer - A | |
| 153. |
Which one of the following substances possesses the highest elasticity-A. steelB. copperC. rubberD. aluminium |
| Answer» Correct Answer - A | |
| 154. |
A bottle has an opening of radius a and length b. A cork of length b and radius `(a+Delta A)` is compressed to fit into the opening completely (See figure). If the bulk modulus of cork is B and frictional coefficient between the bottle and cork is then the force needed to push the cork into the bottle is : A. `(2pimuBb)Deltaa`B. `(pimuBb)Deltaa`C. `(4pimuBb)Deltaa`D. `(pimuBb)a` |
| Answer» Correct Answer - C | |
| 155. |
We spend some energy while stretching a wire. What happens to the energy given to the wire ?A. converted into heat energyB. converted into kinetic energyC. converted into potential energyD. converted into sound energy |
| Answer» Correct Answer - C | |
| 156. |
What happens to the potential energy of the molecules when a solid body is compressed ?A. decreasesB. do not changeC. increasesD. may increase or decrease |
| Answer» Correct Answer - C | |
| 157. |
When a wire is stretched the potential energy of its molecules willA. decreasesB. unaffectedC. increaseD. first increase then decrease |
| Answer» Correct Answer - C | |
| 158. |
The work done per unit volume in stretching the wire is equal toA. stress `xx` strainB. stress / strainC. `1//2` strain `xx` strainD. strain / stress |
| Answer» Correct Answer - C | |
| 159. |
Consider a rod stell having radius of 8 mm and the length of 2 m. If a force of 150 kN stretches it along its length, then calculate the stress and strain in the rod, if the elongation in length is 7.46 mm.A. `7.46 xx 10^(8) N,^(-2)` and `3.73 xx 10^(-3)`B. `7.43 xx 10^(6) Nm^(-2)` and `2.73 xx 10^(-5)`C. `7.28 xx 10^(10) Nm^(-2)` and `2.83 xx 10^(-4)`D. None of the above |
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Answer» If the rod stretches along it length, then the stress produced is the tensile stress whereas the strain produced is longitudinal strain. Given, radius, `r = 8 mm = 8 xx 10^(-3) m`, length, `L = 2m` Force, `F = 150 kN = 15 xx 10^(4) N` Area, `A = pi r^(2) = pi xx (8 xx 10^(-3))^(2) = 201 xx 10^(-6) m^(2)` Increase in length, `Delta L = 7.4 mm = 7.46 xx 10^(-3) Nm^(-2)` stress and strain = ? Stress `= (F)/(A) = (15 xx 10^(4))/(201 xx 10^(8)) = 0.0746 xx 10^(10) Nm^(-2)` `= 7.46 xx 10^(8) Nm^(-2)` Longitudinal strain `= (Delta L)/(L) = (7.46 xx 10^(-3))/(2) = 3.73 xx 10^(-3)` |
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| 160. |
If the angle of shear is `30^(@)` for a cubical body and the change in length is 250 cm, then what must be the volume of this cubical body.A. `81.295 m^(3)`B. `71.309 m^(3)`C. `91.106 m^(3)`D. `83.266 m^(3)` |
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Answer» Given, angle of shear `= 30^(@)` and change in length, `Delta L = 250 cm = 2.5 m` `:.` Shear strain, `tan theta = (Delta L)/(L)` ` implies tan 30^(@) = (2.5)/(L)` `L = (2.5)/(tan 30^(@)) = (2.5)/(0.577) = 4.332 m` Volume, `V = L^(3)` `= (4.332)^(3) = 81.295 m^(3)` |
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| 161. |
Which of the following does not exhibit a shear ?A. twisting of wireB. increasing in length of wireC. wriggling of washed clothesD. bending of beam |
| Answer» Correct Answer - B | |
| 162. |
The reason for the change in shape of a regular body isA. shearing strainB. bulk strainC. normal strainD. longitudinal strain |
| Answer» Correct Answer - A | |
| 163. |
The reason for the change in shape of a regular body isA. bulk strainB. longitudinal strainC. shearing strainD. volume strain |
| Answer» Correct Answer - C | |
| 164. |
The reason for the change in shape of a regular body isA. Volume stressB. Shearing strainC. Longitudinal strainD. Metallic strain |
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Answer» Correct Answer - B |
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| 165. |
If a copper wire of length 0.9 m and cross section `1mm^(2)` is stretched by a load of 1 kg then the extension in the wire will be `(Y_(c )=1.2xx10^(11)N//m^(2) and g=10m//s^(2))`A. 0.013 mmB. 0.075 mmC. 0.11 mmD. 0.13 mm |
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Answer» Correct Answer - B `e=(FL)/(Ay)=(1xx10xx0.9)/(10^(-6)xx1.2xx10^(11))` `=(3)/(4) xx 10^(-4) = 0.75 xx 10^(-4)m` `=0.075 mm`. |
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| 166. |
A load W produces an extension of `1mm` in a thread of radius `r`. Now if the load is made `4W` and radius is made `2r` all other things remaining same, the extension will become.A. `4mm`B. `16 mm`C. `1mm`D. `0.25 mm` |
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Answer» Correct Answer - C |
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| 167. |
A wire of length `50 cm` and cross sectional area of 1 sq. mm is extended by `1mm`. The required work will be `(Y=2xx10^(10) Nm^(-2))`A. `6 xx 10^(-2) J`B. `4xx10^(-2) J`C. `2xx10^(-2) J`D. `1xx10^(-2) J` |
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Answer» Correct Answer - C |
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| 168. |
Identical springs of stecl and copper `(Y_("Steel") gt Y_("copper"))` are equally stretched.A. less work is done on steel springB. less work is done on copper stringC. equal work is done on both the springsD. data not complete |
| Answer» Correct Answer - B | |
| 169. |
(i) Two identical rods, one of steel, the other of copper, are stretched by an identical amount. On which operation more work is expended? (ii) Two identical rods, one of steel, the other of copper, are stretched with equal force. On which operation is more work needed? |
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Answer» Correct Answer - (i) Stretching of steel , (ii) Stretching of Copper |
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| 170. |
A rubber cube of side 10 cm has one side fixed to a horizontal surface. A tangential force of 2000 N is applied on the opposite face. The distance through which the strained side moves will be (Rigidity modulus of the material is `200xx10^(4)N//m^(2), g=10m//s^(2)`)A. 1 cmB. 10 cmC. 1.4 cmD. 20 cm |
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Answer» Correct Answer - A `eta=(Fh)/(A x) " " therefore x=(Fh)/(A eta)` `therefore x=(2000 xx 0.1)/(0.1xx0.1xx2xx10^(6))=1xx10^(-2)m` `=1 cm` |
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| 171. |
A steel wire of length 2.5 m and area of cross section `1.25 mm^(2)`, when it is stretched by a force of 40 N and Y for steel is `2xx10^(11)N//m^(2)`. The extension produced in a steel wire isA. 0.4 mmB. 0.4 cmC. 4 mmD. 4 cm |
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Answer» Correct Answer - A `y=(FL)/(Al)` `therefore l=(40xx2.5)/(2xx10^(11)xx1.25xx10^(-6))=0.4 mm. ` |
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| 172. |
Assertion : identical springs of steel and copper are equally stretched. More work will be done on the steel spring. Reason : Steel is more elastic than copper.A. (a) If both Assertion and Reason are true and the Reason is correctn explanation of the Assertion.B. (b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.C. If Assertion is true, but the Reason is false.D. If Assertion is false but the Reason is true. |
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Answer» Correct Answer - A `Y_("steel") gt Y_("copper")` . So, for the same strain , stress to be produced in steel is more. ltbr gt Also , Work done ` = 1/2 "stress"xx"strain"` Volume `= 1/2Yxxepsilon ^(2)` |
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| 173. |
If the work done in stretching a wire by 1 mm is 2J, then work necessary for stretching another wire of same material but with double radius of corss-section and half the length by 1 mm isA. 4B. 8C. 2D. 16 |
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Answer» Correct Answer - D `w_(1)=(1)/(2) F_(1)l_(1) and w_(2) =(1)/(2)F_(2)l_(2)` `(w_(2))/(w_(1))=(F_(2))/(F_(1)) xx ((A_(2))/(A_(1)))^(2)xx(L_(1))/(L_(2))` |
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| 174. |
The work done in stretching a wire by 0.1 mm is 3 J. Then the work done in stretching another wire of the same material but with double the radius and half the length by 0.1 mm isA. 12 JB. 18 JC. 24 JD. 32 J |
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Answer» Correct Answer - C `(W_(2))/(W_(1)) =((1)/(2)F_(2)l)/((1)/(2) F_(1)l)=(F_(2))/(F_(1))=(r_(2)^(2))/(r_(1)^(2)) xx (L_(1))/(L_(2))=4xx2` `W_(2)=8W_(1)` `=8xx3=24J`. |
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| 175. |
The compressibility of water is `4xx10^-5` per unit atmospheric pressure. The decrease in volume of 100 cubic centimetre of water under a pressure of 100 atmosphere will beA. 0.4 ccB. `4xx 10^(-5) c c`C. `0.025 c c`D. `0.004 c c` |
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Answer» Correct Answer - A |
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| 176. |
To keep constant time, watches are fitted with balance whell made ofA. InvarB. Stainless steelC. TungstenD. Platinum |
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Answer» Correct Answer - A |
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| 177. |
Statement-1: The stretching of a coil is determined by its shear modulus. Statement-2: Shear modulus change only shape of a body keeping its dimensions unchanged.A. Statement-1, is true, Statement-2 is true, Statement-2 is correct explanation for statement-1B. Statement-1 is true, statement-2 is true, statement-2 is NOT a correct explantion for statement-1C. statement-1 is true, statement-2 is falseD. statement-1 is false statement-2 is true |
| Answer» Correct Answer - A | |
| 178. |
Statement-1: The stretching of a coil is determined by its shear modulus. Statement-2: Shear modulus change only shape of a body keeping its dimensions unchanged.A. If both assertion and reason are true and the reason is the correct explanation of the assertion.B. If both assertion and reason are true but reason is not the correct explanation of the assertion.C. If assertion is true but reason is fa lse.D. If the assertion and reason both are false |
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Answer» Correct Answer - A |
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| 179. |
The stretching of a coil spring is determined by its shear modulus. Why? |
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Answer» When a coil spring is stretched, neither its length nor its volume changes, there is only the change in its shape. Therefore, stretching of coil spring is determined by shear modulus. |
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| 180. |
In a U-tube diamter of two limbs are 0.5 cm and 1 cm respectively and tube has filled with water `(T=72"dyne"//cm`) then liquid level difference between two limbs will beA. 0.5 cmB. 0.25 cmC. 0.293 cmD. none of these |
| Answer» Correct Answer - C | |
| 181. |
The property of metals which allows to form a thin wires beyond their elastic limit without rupture isA. ductilityB. malleabilityC. elasticityD. hardness |
| Answer» Correct Answer - A | |
| 182. |
The modulus of elasticity is dimesionally equivalent toA. stressB. strainC. surface tensionD. elastic fatigue |
| Answer» Correct Answer - A | |
| 183. |
Length of an elastic string is x then tension 5N is applied and its length will be y when tension 7 N. What will be its original length ?A. `(2x+y)/(2)`B. `(2y-yx)/(2)`C. `(7x-5y)/(2)`D. `(7y+5x)/(2)` |
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Answer» Correct Answer - C `x=L+l_(1) " "therefore l_(1)=x-L` `y= L+l_(2) " " therefore l_(2) =y-L` `(F_(2))/(l_(2))=(F_(1))/(l_(1))` `(7)/(y-L)=(5)/(x-L)" " therefore L=(7x-5y)/(2)` |
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| 184. |
An object of volume V is submerged in a liquid of density `rho`. It has flat bottom of area A which is at depth of H in the liquid and a dome shaped top find the total force of liquid acting on the top of the object.A. `|rhoHAg-rhoVg|` and upwardB. `|rhoHAg-rhoVg|` and downwardC. `rhoVg` downwardD. `rhoVg` and upward |
| Answer» Correct Answer - B | |
| 185. |
A sample of metal weights 210 grams in air 180 grams n water and 120 grams in an unknown liquid thenA. the density of metal is `3g//cm^(3)`B. the density of metal is `7g//cm^(3)`C. density of metal is 4 times the density of the unknown liquid.D. the metal will float in water. |
| Answer» Correct Answer - B | |
| 186. |
Water stands upto a height `h` behind the vertical wall of a dam what is the net horizontal force pushing the dam down by the stream if width of the dam is `sigma`? `(rho=` density of water)A. `2hsigmag`B. `(h^(2)sigmarhog)/(2)`C. `(h^(2)sigmarhog)/(4)`D. `(hsigmarhog)/(4)` |
| Answer» Correct Answer - B | |
| 187. |
A siphon has a uniform circular base of diameter `8//sqrt(pi) cm` with its crest `A, 1.8 m` above the water level vessel `B` is of large cross section (`g= 10 m//s^(2)` and atmospheric pressure `P_(0) = 10^(5) N//m^(2))`. |
| Answer» Correct Answer - (i). `6sqrt(2)m//s,(ii). 9.6sqrt(2)xx10^(-3)m^(3)//s, (iii). 4.6xx10^(4)N//m^(2)` | |
| 188. |
Two vessels A and B have the same base area and contain water to the same height but the mass of water in A is four times that in B. The ratio of the liquid thrust at the base of A to that at the base of B isA. `4:1`B. `2:1`C. `1:1`D. `16:1` |
| Answer» Correct Answer - C | |
| 189. |
To what height h should a cylindrical vessel of diameter d be filled with a liquid so that the total force on the vertical surface of the vessel be equal to the force on the bottom-A. h=dB. h=2dC. h=3dD. h=d/2 |
| Answer» Correct Answer - D | |
| 190. |
For a gas elastic limitA. ExistsB. Exists only at absolute zeroC. Exists for a perfect gasD. Does not exist |
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Answer» Correct Answer - A |
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| 191. |
A wire of length L and radius a rigidlyl fixed at one end. On stretching the other end of the wire with a force F, the increase in its length is L, if another wire of same material but of length 2 L and radius 2 a is stretched with a force 2 F, the increase in its length will beA. `l`B. `2l`C. `(l)/(2)`D. `(l)/(4)` |
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Answer» Correct Answer - A |
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| 192. |
Calculate the work done agains surface tension in blowing a soap bubble from a radius 10 cm to 20 cm if the surface tension of soap solution is `25xx10^(-3)N//m` then compare it with liquid drop of same radius. |
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Answer» (i). For soap bubble: Extension in area `=2xx4pir_(2)^(2)-2xx4pir_(1)^(2)=8pi[(0.2)^(2)-(0.1)^(2)]=0.24pim^(2)` Work done `W_(1)=` Surface tension `xx` extension in area `=25xx10^(-3)xx0.24pi=6pixx10^(-3)J` (ii). For liquid Drop: In case of liquid drop only one free surface, so extension in area will be half of soap bubble `thereforeW_(2)=(W_(1))/(2)=3pixx10^(-3)J` |
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| 193. |
A big drop is formed by coalescing 1000 small droplets of water. What will be the change in surface energy What will be the ratio between the total surface energy of the droplets and the surface energy of the big drop? |
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Answer» By conservation of volume `(4)/(3)piR^(3)=1000xx(4)/(3)pir^(3)imliesr=(R)/(10)` Surface enegy of 1000 droplets `=1000xxTxx4pi[(R)/(10)]^(2)=10(Txx4piR^(2))` Surface energy of the big drop `=Txx4piR^(2)` Surface energy will decrease in the process of formation of bigger drop, hence energy is released and temperature Increases `therefore("total surface energy of 1000 droplets")/("surface energy of big drop")=(10(Txx4piR^(2)))/(Txx4piR^(2))=(10)/(1)` |
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| 194. |
A piece of cork starts from rest at the bottom of a lake and floats up. Its velocity v is plotted against time t. Which of the following best represents the resulting curve? |
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Answer» Correct Answer - A As the cork moves up, the force due to buoyancy remains constant. As its speed increases, the retardig force due to viscosity increases, being proportional to the speed. Thus the acceleration gradually decreases. |
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| 195. |
On stretching a wire, the elastic energy stored pre unit volume isA. `Fl//2AL`B. `FA//2L`C. `FL//2A`D. `FL//2` |
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Answer» Correct Answer - A |
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| 196. |
A sphere or radius 3 cm is subjected to a pressure of 100 atm. Its volume decreases by 0.3 cc. What will be its bulk modulus?A. `4 pi xx 10^(5) atm`B. `4 pi xx 3 xx 10^(3) atm`C. `4 pi xx 10^(6) atm`D. `4 pi xx 10^(8) atm` |
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Answer» Correct Answer - b Given, `r = 3cm, Delta V = 0.3 cc` Bulk modulus, `B = 0 (pV)/(Delta V) = (100 xx (4)/(3) pi r^(3))/(0.3)` `= 4 pi xx 3 xx 10^(3) atm` |
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| 197. |
A 4-kg block extends a spring by 16 cm from its unstretched postion .The block is removed and a 0.5 -kg boby is hung from the same spring If the spring is then stretched and released , what is the time period of oscillations of the mass suspendrd ? What is the force constant of the spring ? |
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Answer» Correct Answer - `0.284s 25kg m^(-1)` |
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| 198. |
A wire is loaded by a weight of density `9g//cm^(3)` and stretched to a length of 98 cm. On immersing the weight in water the length shortens by 2.5 mm. Then the original length of the wire will be `[rho_(w)=1 gm//cm^(3)]`A. 95.75 cmB. 98.75 cmC. 90. 75 cmD. 85.75 cm |
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Answer» Correct Answer - A `L+X=98 " " therefore x=98-L` `L+y=98-0.25 " " therefore y=98-L-0.25` `T_(1) prop x and T_(2) prop y` `(T_(1)-T_(2))/(T_(1))=(x-y)/(x)=(0.25)/(98-L)` `(V rho g)/(V rho_(1)g)=(0.25)/(98-L)` `(rho)/(rho_(1))=(0.25)/(98-L)` |
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| 199. |
A steel ball is floating in a trough of mercuty. If we fill the empty part of the trough with water, what will happen to the steel ball ?A. it will continue in its positionB. it will move upC. it will move downD. it will execute vertical oscillations |
| Answer» Correct Answer - B | |
| 200. |
The following four wires are made of same material. Which of these will have the largest extension when the same tension is applied?A. diameter 1 mm and length 1 mB. diameter 2 mm and length 2 mC. diameter 0.5 mm and length 0.5mD. diameter 3 mm and length 3 m |
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Answer» Correct Answer - C (c) Elongation of the wire `Deltal=(Fl)/(AY)` or `Deltal prop (l)/(d^(2))" "(because A=(pi)/(4)d^(2))` Therefore, `Deltal` will be maximum for that wire for which `(1)/(d^(2))` is maximum. |
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