Thermal Expansion Questions and Answers

D C moves to left A to night A vessel containing a liquid is heated with its contents The pressure at the bottom of vessel due to the liquid should no evaporation take place A increase C increases if Ysq 3 vessel B decrease D decreases if Yg 3 vessel academy com 61

c 340 N d 6800 N A steel tape measures the length of copper rod as 90 00 cm when both are at 10 C the calibration temperature for the tape What would the tape read for the length of the rod when both are at 30 C given steel 1 2 x 10 5C and ac 1 7 x 10 5PC a 89 00 cm b 90 21 cm d 90 01 cm c 89 90 cm The density of a substance decreases from

11 Consider a compound slab consisting of two different material having equal area cross section and thermal conductivities K and 4K The equivalent thermal conductivity of the slab is 0 A A 1 K 2 1 5 K 3 2 K 4 2 5 K K 4K B B 0 0 0

1 2 Two rods of different materials having coefficients of thermal expansion a and a2 and Young s moduli Y and Y respectively are fixed between two rigid massive walls The rods are heated such that they undergo the same increase in temperature There is no bending of the rods and junction does not shift If a and a are in the ratio 2 3 the thermal stress developed in the two rods are equal provided Y Y is equal to 2 1 2 3 3 3 2 2 1 1 4 4 9

10 The coefficient of volume expansion of material of a metre scale is 18 x 105 K Find the fractional change in its length when temperature is changed by 20 C 1 36 x 104 A 2 18 x 104 3 12 x 10 4 4 6 x 104 13

Q1 The end Q and R of two thin wires PQ and RS are soldered joined together Initially each of the wires has a length of 1 m at 10 C Now the end P is main tained at 10 C while the end S is heated and main tained at 400 C The system is thermally insulated from its surroundings If the thermal conductivity of wire PQ is twice that of the wire RS and the coefficient of linear thermal expansion of PQ is 1 2 x 10 5 K 1 2016 the change in length of the wire PQ is B 0 90 mm A 0 78 mm C 1 56 mm D 2 34 mm

4 Inc 76 Stress vs strain graph for two different wires A and Bis given If Y and Y are Young s modulus of material A B then Stress 1 YA 3 YB 3 Y 3Y R niboo 15 30 A B Strain 2 3 YA YB 4 3Y YR B

2 A wire has resistance of 3 1 2 at 30 C and 4 5 Q at 100 C The temperature coefficient of resistance to the wire is approximately 1 12 x 10 4 C 1 2 24 x 10 4 C 1 3 32 x 10 C 1 4 7 x 10 3 C 1 Hint Use R R 1 R 1 a AT

44 Two gases A and B having the same temperature T same pressure P and same volume V are mixed If the mixture is at the same temperature and occupies a volume V the pressure of the mixture is 1 2P Bond P 3 2 2 P 4 4P

A steel wire of cross sectional area 0 5 mm is held between two fixed supports If the wire is just taut at 20 C determine the tension in N when the temperature falls to 0 C Coefficient of linear expe 1 2 x 10 5 C and its Young s modulus is 2 0 x 10 N m

2 Consider the situation shown in figure The wire AB is slide on the fixed rails with constant velocity v If the wire AB is replaced by a semicircular wire the magnitude of the induced current will X X X X X X V X X X X X B X A increase B remain the same C decrease D increase or decrease depending on whether the semicircle bulges towards the y from it

16 An anisotropic material has coefficient of linear thermal expansion a1 a2 and a3 along x y and z axis respectively Coefficient of cubical expansion of its material will be equal to A a az a az B B 2a2 3a3 C 3a1 2a2 az A A 3 D 3

This section contains 35 SINGLE CORR TYPE questions Each question has 4 Read More f two rods of length L and 2L having coefficient of linear expansion a and 2a respectively are connected end to end The average coefficient of linear expansion of composite rod is O O N W 50

f a metal wire is stretched much beyond its elastic limits yield point and released It will Come back to original length O Loss its elastic property completely Contract only upto its length at elastic limit Contract but final length is more than initial length

The r m s velocity of hydrogen molecules at tempreature T is seven times the r m s velocity of nitrogen molecules at 300 K This temperature T is Molecular weights of hydrogen and nitrogen are 2 and 28 respectively A B C D 1050 K 1700 K 1350 K 2100 K

NY75 C 2 3 33 C Two spheres of different materials one having radius double of other and wall thickness 1 4 of other are filled with ice If time required to completely melt the ice is 25 min for larger radius sphere and 16 min for smaller radius sphere then ratio of thermal conduction coefficient for material of larger radius to that of thermal conduction coefficient for mate rial of smaller radius sphere will be 1 4 5 2 5 4 3 8 25 1 1 25 It is placed in a furnace and it is observed that RPMT 2010 RPMT 2010

Area of cross section of two rods of equal lengths are A and A and thermal conductivities are K and K Specific H are S and S condition for equal heat flow is 1 K K 2 K S K S 3 K K A S A S 4 K A K A

14 Find the strain of a brass rod of length 100mm which is subjected to a tensile load of 50KN when the extension of rod is I equal to 0 1mm a 0 01 b 0 001 c 0 05 d 0 005

One quality of a thermometer is that its heat capacity should be small If P is mercury thermometer Qis resistance thermomerter and R thermocouple type then 1 P is best R worst 2 R is best P worst 3 R is best Q worst 4 P is best Q worst is wrapped in wet hanky

Suppose we fill a glass flask with a liquid whose real expansivity is three times the linear expansivity of glass On heating Question Type Single Correct Type 1 2 3 4 The liquid level will increase The liquid level will decrease The liquid level will exactly remain same The liquid level will approximately

N 26 81 In the above problem to be changed by 1 increase by 20 K 3 increase by 20 C 2 53 36 in order to increase the efficiency of the engine by 20 its sink temperature will ha 198k 472 73R 2 decrease by 293 K 4 decrease by 20 C increase the efficiency of 20 its source temperature will have to char

Two moles of helium gas are taken along the path ABCD as shown in diagram The work done by the gas is Question Type Single Correct Type 1 2000R 1 2 In 3 2 500R 3 In 4 3 500R 2 In 20000 16 9 16 D A 20 15 10 5 A 250 500 750 1000 T K

10FI YA A bar is subjected to axial forces as shown If Y is the modulus of elasticity of the bar and A is its cross section area its elongation will be 4F 2F 8FI YA 4FI YA 6FI 2 2F hr 1 min

By how much should the temperature of a brass rod be increased so as to increase its length by 1 Given for brass is 0 00002 O Cick here to view this option et No 341401 D Click here to view this option D el tu 241401 Click here to view this option Ref No 241401

148 If a bimetallic strip is heated it will 1 Bend towards the metal with lower linear thermal expansion coefficient 2 Bend towards the metal with higher linear thermal expansion coefficient 3 Not bend at all

Three rods of the same dimensions have thermal conductivities 3k 2k and k They are arranged as shown with their ends at 100 C 50 C and 0 C The temperature of their junction is 50 C 100 Cr 75 C 200 3 3k 100 LOC 40 C 2k k new in 0 C

on the temperature range A A solid and a hollow sphere of same diamete and same material when heated for the same temperature rise will expand by the same amount R The change in volume is independent of the original mass but depends on original volume

64 Thermal Properties of Matter The coefficient of linear expansion of a crystalline substance in one direction is 2 10 C and in every direction perpendicular to it is 3 x 10 4 PC The coefficient of cubical expansion of crystal is equal to 1 5 x 10 4 C 2 4 x 10 4 C

3 Two bodies A and B of same mass area and surface finish with specific heats SA and Sa SA Sa are allowed to cool for given temperature range Temperature varies with time as 1 3 0 0 0 0 A 2 0 0 0 0 0 A B B

A uniform copper rod of length 50 cm and diameter 3 0 mm is kept on a frictionless horizontal surface at 20 C The coefficient of linear expansion of copper is 2 0 x 10 5 K and Young s modulus is 1 2 x 10 1 N m The copper rod is heated to 100 C then the tension developed in the copper rod is 2 36 10 N 4 Zem 1 12 x 10 N 3 18 x 10 N

On heating a uniform metallic cylinder length increases by 3 The area of cross section of its base will increase by 1 1 5 3 9 2 3 4 6

12 The apparent coefficient of expansion of a liquid when heated in a brass vessel is X and when heated in a tin vessel is Y If a is the coefficient of linear expansion for brass the coefficient of linear expansion of tin is 1 X Y 3a 3 2 X 3a Y 3 X Y 2c 3 13 The coefficient of volume expansion of glycerin is X Y 20 2

3 273 C 4 273 K A hole is drilled in a copper sheet The diameter of hole is 4 24 cm at 27 0 C Diameter of the hole when it is heated to 35 C is 1 Less than 4 24 cm 2 Equal to 4 24 cm 3 More than 4 24 cm 4 Data insufficient 12

1 5 7 10 C 2 0 63 10 PC 3 1 9 10 c 4 16 1 x 10 rc Ratio among linear expansion coefficient c area expansion coefficient B and volume expansion coefficient y is 1 1 2 3 3 4 3 2 2 3 2 1 4 All of these

The coefficients of apparent expansion of a liquid when determined using two different vessels A and B are y and Y2 respectively If the coefficient of linear expansion of the vessel A is a the coefficient of linear expansion of the vessel B is A B C D ay1Y2 Yi 12 11 Y2 2a Y1 Y2 a 3 Y1 2 3 a Correct Answer

A steel rod of length 1m is heated from 25 C to 75 C keeping its length constant The logitudinal strain developed in the rod is Given coefficient of linear expansion of steel 12 10 6 C A 6 x 10 3 C 6x 10 5 6 10 4 zero My Answer Correct Answer

33 The density of water at 20 C is 998 kg m and at 40 C 992 kg m The coefficient of volume expansion of water is 1 10 4 C 2 3 10 4 C milen 3 2x 10 4 C 4 6 10 4 C 4 If 1 g of steam at 100 C steam is mixed with 1 g

3 1 25 x 10 1 Nm 2 4 16 x 10 Nm 8 Two wires of length I radius r and length 21 radius 2r respectively having same Young s modulus are hung with a weight mg Net elongation is 2 1 3 3 mgl Y 3 mgl 2mr Y 2 mgl 3r Y 3 mgl 4rr Y

2 Three rods equal length 1 connected in such away 42 that they from an equilateral triangle PQR Q be the mid point of PQ and OR remains constant for small in increment of temperature Linear expn coefficienents of PR and PQ are same a and linear expn coefficients of PQ is than 1 4 3 3 p4 R 2 3 4 4

13 The value of coefficient of volume expansion of glycerin is 5 x 10 4K 1 The fractional change in the density of glycerin for a rise of 40 C in its is Re AIPMT 2015 temperature 1 0 010 3 0 020 2 0 015 4 0 025 ET AIIMS

Example 13 A steel wire 4 0 m in length is stretched through 2 0 mm The cross sectional area of the wire i 2 0 mm If Young s modulus of steel is 2 0 10 Nm2 Find m 6Y The energy density of wire The plastic potential in the wim

A bimetallic strip consists of metals A and B It is mounted rigidly as shown The metal A has higher coefficient of expansion compared to that of metal B When the bimetallic strip is placed in both it will 1 2 ect Answer 4 sunattempted Bend towards the right Not bend but shrink Neither bend nor shrink Bend towards the left AB

67 An iron tyre is to be fitted onto a wooden wheel 1 metre in diameter The diameter of the tyre is 6 mm smaller than that of the wheel The tyre should be heated so that its temperature increases by a minimum of coefficient of volume expansion of iron is 3 6 10 5 C X 1 167 C 3 500 C 2 334 C 4 1000 C

Do 4 4 9 A glass flask of volume 200 cm is just filled with mercury at 20 C The amount of mercury that will overflow when the temperature of the system is raised to 100 C is Yglass 1 2 x 10 5 C Ymercury 1 8 x 10 4 C 1 2 15 cm 2 2 69 cm 3 2 52 cm 4 2 25 cm Solids expand on heating because 1 2

winter when the average temperature is 18 C The track consists of sections of 12 0 m placed on after the other How much gap in cm should be left between two such sections so that there is no compression during summer when the maximum temperature goes to 48 C Coefficient of linear expansion of iron 11 x 10 6 C Question Type Numerical Type

At any instant the ratio of amount of radioactive substance is 2 1 If their half lives are respectively 12 and 16 hours then after 2 days what will be the ratio of amount of substance left 1 1 2 1 1 4

A bimetallic strip made of steel and brass each of thickness 2 8 mm heated through 200 C abrass 19x10 6 C a steel 1 It bends with concave side steel rod II IT bends with convex side steel rod III It radius of curvature 2m on convex side brass IV Expansion of steel is greater than brass A I and III B I and II C III and IV D I II and IV 12x10 6 C Then

A P V diagram for a thermodynamic process is shown in the figure If T TB then choose the correct option during the process PA 3Po Po V 0 B 2Vo Temperature continuously increases Temperature continuously decreases Temperature first increases then decreases

m A given metal wire has length 1m linear density 0 6 and uniform cross sectional area 10 7 m is fixed at both ends The temperature of wire is decreased by 40 C The fundamental frequency of the transverse wave is Y 2x 10 1 coefficient N m of linear expansion of metal is 1 2 x10 C A B C D 0 5 Hz 2 Hz 1 Hz 2 5 Hz

A horizontal piston cylinder arrangement encloses a gas at a pressure Po The atmospheric pressure is also Po Now a particle of mass m strikes the piston of identical mass m with a horizontal speed u and sticks to it Subsequently the piston moves without friction and compresses the gas The process of compression can be assumed to be adiabatic In this Po m process A when the piston comes to rest at maximum compression the internal energy of gas would 1 have increased by mu 4 B During the time interval starting from the mass striking the piston to the maximum compression of the enclosed gas the work done by the gas is mu When the piston comes to rest after compressing the gas the internal energy of the gas would have increased by the amount more than mu 4 D During the compression of the gas till the time when piston comes to rest work done by the gas is less than mu 4