Fluids Questions and Answers

1 Equal masses of water and a liquid of relative density two are mixed together then mixture has a relative density of 1 2 3 2 4 3 3 3 2 4 3 essel contains a liquid of density p as shown 2 pressure at the point P is no e fufera fe 1 2 3 farger

12 cm s When water spreads on a glass plate the for between the water molecules and glass mo ecules is called 1 Surface tension 2 Cohesive force 3 Adhesive force 4 None of the

4 volumes of A B and C will become equal at equilibrium A volume V of a viscous liquid flows per unit 8 time due to pressure head of AP along a pipe of diameter D and length 7 Instead of this pipe a set of four pipes each of diameter D 2 and length 27 is connected in parallel to the same pressure head of AP Now the volume of the liquid flowing per unit time is 1 V 2 V 4 3 V 6 4 V 8

4 Height of The given figure shows three soap bubbles A 7 B and C are prepared by blowing the capillary tube with stop cocks S S S and S With stop cock S closed and S S and S opened then A S HS HIS L E B 1 C and A will both start collapsing with volume of B increasing 2 B will start collapsing with volumes of A and C increasing 3 C will start collapsing with volumes of A and B increasing 4 volumes of A B and C will become equal at equilibrium liquid flows per ur

When an air bubble comes from the bottom of a lake to the top surface then its radius 1 Increases 2 Decreases 3 Does not change 4 Becomes zero

ALLEN 6 Three tubes A B and C are connected to a 6 horizontal pipe in which an ideal liquid is flowing The radii of the tubes A B and C at the junction are respectively 2 cm 1cm and 2 cm It can be said A B C 1 The height of the liquid in the tube A is maximum 2 Height of the liquid in the tubes A and B is same 2 3 Height of the liquid in the tubes A B and C is same night of the liquid in the A and C is same bubbles A

A solid is completely immersed in an ideal 5 liquid The force exerted by the liquid on the solid will 1 increase if it is pushed deeper inside the liquid 2 change if its orientation is changed keeping it inside the liquid 3 decrease if it is taken partially out of the liquid

A vessel contains a liquid of density p as shown in figure The gauge pressure at the point P is H 1 hpg 3 H h pg H h OF 2 Hpg 4 H h pg cos 0 ubbla comes from the bottom of figur 3 H www 1 hpg 3 H h pg

A metallic sphere with an internal cavity weights 40gm in air and 20gm in water If the density of the material with the cavity is 2gm CC then the volume of the cavity is 1 15CC 3 25CC 2 20CC 4 30CC

5 If a solid is floating on a liquid then which of the thermal following statements is wrong a coefficient of linear expansion of solid y thermal coefficient of cubical expansion of liquid 1 If y 3a then upon heating the solid will float with more fraction of volume in the liquid 2 If y 3x then upon heating the solid will float with lesser volume in the liquid 3 If y 3a then upon heating the fraction of volume of solid in liquid remains constant Both 2 3

A tank is filled with a liquid upto a height H A small hole is made at the bottom of this tank Consider t be the time taken to empty first half of the tank and to be the time taken to empty rest half of the tank t Then determine the ratio

Consider the barometer shown in figure Density of mercury A small hole is made at point S as shown The mercury com out from this hole with speed v equal to ptions 2gh 2gH 2g H h none of these h H S Mercury

106 The ratio of the pressure P on a swimmer 10 m below the water surface of a lake to that of the pressure on the surface of water P Atmospheric pressure 1 10 Pa 1000 kg m 10 m s is ut be rose be de 38 10 5 1 a adop bassess be doing sony base de Daze wede bas2 1 10 Pa p 1000 kg m g 10 m s 115 2 2 4 3 3 Zero

1 A log of wood floats in water with of its volume above the surface What is the density of wood A 750 gm cc 750 kg m 250 gm cc 250 kg m

A liquid drop of diameter D is divided into 27 equal droplets If the surface tension is T then the change in energy will be Question Type Single Correct Type 1 3 D T 2 D T 3 2 D T

A water tank standing on floor has two small holes punched in vertical wall one above the other The holes are 2 4 cm and 7 6 cm above the floor If the jet of water from holes hit the floor at the same point then height of water in tank is 10 cm 5 cm 2 5 cm 6 8 cm

A log of wood floats in water with 1 of its 4 volume above the surface What is the density of wood Question Type Single Correct Type 1 750 gm cc 2 750 kg m3 3 250 gm cc 4 250 kg m3

A ball is made of a material of density p where Poil P Pwater with Poil and Pwater representing the densities of oil and water respectively The oil and water are immiscible If the above ball is in equilibrium in a mixture of this oil and water which of the following pictures represents its equilibrium position a c water oil water oil 2000 4444 Baldo Pippbi44444 AAAAAAAAAA CRAPBAAAAA b d oil water oil 000 1414 1444444 4444444444 444 infote 4 water

1 A spherical raindrop of initial mass Mo and initial radius R falls freely from rest Let p be the constant density and r the radius at time t Assume that the drop maintains it s spherical shape The drop loses mass at the rate dm dt 47kpr where k is a constant Define te R Select the correct statement s 1 The speed of the drop at time te 2 is 15gR 8k 2 The rate of mass loss goes to zero as time ttc 3 The drop loses all it s mass in time te 4 The momentum approaches MogB 4k as t to

57 Water rises in a capillary upto a height of 4 cm If it is titled to 30 from the vertical then the length of water column in it will be 4 cm 3330 i 8 1 cm 2 8 3 cm 3 4 cm 4 2 cm

The current velocity of a river grows in proportion to the distance from its bank and reaches the maximum value vo in the middle Near the banks the velocity is zero A boat is moving along the river in such a manner that it is always perpendicular to current and the speed of the boat in still water is u If the width of river is I the distance through which the boat crossing the river will be carried away by the Ivo Current in

A hydraulic lift is designed such that cross sectional area of its arms are 5 cm 10 m Find the force applied by mechanic or smaller area in order to lift a car of 5000 kg A B C 5 N 2 5 N 10 N 12 N

If the Ka radiation of Mo Z 42 has a wavelength of 0 71 calculate wavelength of the corresponding radiation of Cu i e Ka for Cu Z 29 assuming b 1 1 2 52 2 1 52 A 3 1 98 4 3 22

A simple pendulum with a metallic bob has a time period T The bob is now immersed in a non viscous liquid and oscillated If the density of the liquid is 1 4th of the metal what will be the time period of the same pendulum now

127 A drop of water and a soap bubble have the same radii Surface tension of soap solution is half of that of water The ratio of excess pressure inside the drop and bubble is A 1 2 B 2 1 C 1 4 D 1 1

73 When the u tube shown below is in rest th liquid stands at the same level in both the tub But as indicated a height difference h occurs w the system is given an acceleration a towards right Here h is equal to aL 1 2g L 2 2a a

Water flows along a horizontal pipe whose or section is not constant The pressure is 1 cm of where the velocity is 35 omis At a point where velocity is 65 cm sec The pressure will be 6 0 89 cm of Hg

94 A cubical container was initially full with a lic container is now accelerated horizonta acceleration a such that one third of the spilled out Find the value of a 1 g 2 g 3 1 3 2g 3 4 g 2 fficient length is dip

Water is filled in a container upto height of 3m A small hole of area Ao is punched in the wall of the container at a height 52 5 cm from the bottom The cross sectional area of the container is A If Ao A 0 1 then 1 is where v is the velocity of water coming out of the hole A 50 m s B 50 5 m s C 51 m s D 52 m s A A You Missed

16 Two identical holes each of cross sectional area A are opened on the opposite sides of a wide vertical vessel filled with water The difference in vertical height of the two holes is h The resultant force of reaction of wa ter flowing out of vessel is A hpgA C 2hpgA B hpgA D hpgA 4

Water is flowing through a channel that is 12 m wide with a speed of 0 75 m s The water then flows into four identical channels that have a width of 4 0 m each The depth of the water does not change as it flows into the four channels What is the speed of the water in one of the smaller channels Question Type Single Correct Type 1 0 56 m s 2 2 3 m s Totul NUL 3 0 25 m s

A certain number of spherical drops of a liquid of radius r coalesce to form a single drop of radius R and volume V If T is the surface tension of the liquid then 2014 energy 4VT is released R r energy 3VT is absorbed R energy 3VT 1 1 r is released Incorrect Correct

0 The mass of a body is 200 g Keeping 7 part of its volume exposed to air the body is floating in mercury If the specific gravity of mercury is 13 6 then what wil be the specific gravity of the body 6 4

Air in a sealed syringe is slowly compressed by moving the piston The temperature of the air stays the same D air syringe Which statement about the air is correct A The pressure of the air decreases because its molecules now travel more slowly B The pressure of the air decreases because the area of the syringe walls is now smaller C The pressure of the air increases because its molecules now hit the syringe walls more frequently The pressure of the air increases because its molecules now travel more quickly H piston

27 0 If work done in increasing the size of rectangular soap film with dimensions 8 cm x 3 75 cm to 10 cm x 6 cm is 2 x 10 4 J The surface tension of film in newton per meter is 2 1 x 10 2 1 65 x 10 2 3 3 x 10 2 4 2 x 10 Solution

Please explain clearly 5 A closed vessel in the shape of a truncated cone having semivertex angle 53 have top and bottom radii r and 3r The vessel is full of a liquid of density p The force applied by the walls of the container on the liquid is 1 pg Fr 3r 2 3 r pg

A closed rectangular tank is completely filled with water and is accelerated horizontally with an acceleration towards right Pressure is i maximum at and ii minimum at B Question Type Single Correct Type i B ii D 2 i C ii D 4 3 i B ii C D i B ii A a

A light cylindrical vessel of radius r is kept on a rough horizontal surface so that it cannot slide but can topple It is filled with water upto a height 2h and a very small hole of area a is punched it so that the water that will come out of it falls at the maximum distance from its wall along horizontal surface Water comes out horizontally from the hole The maximum value of h for which the cylinder does not topple is 1 2 3 Question Type Single Correct Type 2 r a Hole 3 r 2a 2r 2h

A rectangular tank is filled completely with water A hole at its bottom is unplugged The graph between the velocity of efflux through a small hole vs depth of water h from the top of tank is Question Type Single Correct Type 2 3 4 L h h h

CUT 18 Velocity of flow of water in a horizontal pipe is 10 m sec Then the velocity head of water will be g 10 m sec 1 100 m 2 10 m 3 50 m 4 5 m 19 The adiabatic elasticity of hydrogen gas y 1 4 at

is no flow 6 Radius of an air bubble at the bottom of the lake is r and it becomes 2r when the air bubble rises to the top surface of the lake If the atmospheric pressure is p cm then the depth of the lake is Neglect pressure difference due to surface tension 1 2p cm 2 8p cm 3 4p cm 4 7p cm

54 A body of mass M and volume V is floating in a liquid of density o When an excess mass m is placed on the body then it just sinks in the liquid The value of excess mass is 1 Vo M 3 M Vo 2 Vo M Vo M 4 Vo

3 Eo V 4 91 92 93 80 27 small drops of same size are charged to V vo each If they coalesce to form a single large dro then its potential will be 1 3V 2 9V 5717

27 similar drops of mercury are maintained at 10V each All these spheric drops combine into a single big drop The potential energy of the bigger drop is times that of a smaller drop Answer

2 4RTo 4 2RT In 2 1 2RT 3 BRT 35 A body freely floats in a liquid contained in a vessel The whole system fails freely under grav The gram upthrust on the body is 1 Equal to weight of body in air 2 Equal to weight of liquid displaced 3 Equal to weight of the immersed portion 4 Zero

A long cylindrical vessel is half filled with a liquid When the vessel is rotated about its own vertical axis the liquid rises up near the wall If the radius of vessel is 5 cm and its rotational speed is 2 rotations per second then the difference in the heights between the centre and the sides in cm will be A B 2 0 1 2 C 0 1 D 0 4

2R 30 A cubical block of side a and density p slides over a fixed inclined plane with constant velocity v There is a thin film of viscous fluid of thickness T between the plane and the block The coefficient of viscosity of the film will be 1 pagt sine pagt tan e pagt cose

relative density mersed What e top of wood of metal 14 13 it consists rical plug of of length 10 ottom of the up and the ermine the The float ssless P and 2p 7 49 The interf respectively lies at the point A in a U tube at rest The height of liquid column above A is 8a 3 where AB a The cross sectional area of the tube is S With what angular velocity the tube must be whirled about a vertical axis at a distance a such that the interface of the liquids shifts towards B by 2a 3 A a Figure 7 114 8a 3 2p B

An iceberg is floating partially immersed in sea water The density of sea water is 1 03 gm cm and that of ice is 0 92 gm cm What is the fraction of the total volume of the iceberg above the level of sea water In cann

17 Trees have a special tissue called xylem through which water rises from root to the branches Assuming tissue to be of uniform cross section find vest maximum radius of xylem tissue in a 10 m high coconut tree so that water can rise up to the top surface tension of water 0 1 N m and angle of contact of water with xylem tube 60 g 10 m s 1 1 cm 2 1 mm