Fluids Questions and Answers

36 A mercury drop of radius 1 0 cm is sprayed inte 10 droplets of equal sizes The energy expender in this process is surface tension of mercury is equal to 32 x 10 Nm 1 3 98 x 104 J 2 8 46 x 104 J 3 3 98 x 10 J

Due to capillary action water rises to a height of 1 16 3 cm in a capillary of length 18 cm above the water level If the tube is cut at height of 12 cm 1 Water will come as fountain from the capillary tube 2 Water will stay at a height of 12 cm in the capillary tube but radius of curvature at top will increase 3 Water will stay at a height of 12 cm in capillary tube but radius of curvature at top will decrease

A piece of wood is floating in water kept in a 34 bottle The bottle is connected to an air pump Neglect the compressibility of water If more air is pushed into the bottle from the pump the piece of wood will float with 1 Larger part in the water 2 Lesser part in the water 3 Same part in the water as earlier 4 It will sink impletely filled with

What should be the pressure inside a small ait bubble of 0 1 mm radius situated just below the water surface Surface tension of water 7 2 10 N m and atmospheric pressure 1 013 105 N m 1 2 012 105 N m 2 2 012 104 N m 3 1 027 105 N m 4 1 027 104 N m

4 The all times If the water level falls by 4 cm every hour determine the shape of the jar i e specify x as a function of y The radius of drain hole is 2 mm and can be assumed to be very small water clock jug is such that water level descends at a constant rate at compared to x Drain hole X

The flow speeds of air on the lower and upper surfaces of the wing of an aeroplane are v and 2 v respectively The density of air is p and surface area of wing is A The dynamic lift on the wing is Question Type Single Correct Type 1 pv A 2 2 pv A

2 100 A conical container of radius R 1m and height H 5m is filled completely with liquid There is a hole at the bottom of container of area 10 m see figure Time taken to empty the conical container is n 10 sec Then find the value of n Take g 10 m s R

A 20 cm long capillary tube is dipped in water The water rises up to 8 cm If the entire arrangement is put in a freely falling elevator the length of water column in the capillary tube will be a 10 cm b 8 cm c 20 cm d 4 cm

3 A small hole of radius r is made in a container filled with liquid of density p as shown in the figure kept in atmosphere at pressure P A thin capillary of length I is attached to the hole the viscosity of the liquid is n Initially the capillary is closed using a cork to avoid flow of liquid which is then removed to start the flow find a Frictional force between capillary and the cork to stop liquid from coming out b Speed of efflux just after cork is removed c Horizontal range of the liquid H 2 2 pngHr PgHr 2 16nl 16nl PgHr pr pngHr gH H 2 b pngHr pgr 4 pngHr pr gH pr 16nl 16ml pgHr

An oil drop carries six electronic charge has mass of 1 6 x 10 12 g and falls with terminal velocity in air What magnitude of vertical electric field is required to make drop upward with same speed as it was for only moving downward 16 KN C 1 32 7 KN C 1 48 5 KN C 1 0 68 KN C 1

A small orifice of area a is at the bottom of a tube of cross sectional area 3a Water filled up to height H in it and orifice is opened Acceleration of surface of water when water level falls to height H is 3g 9

2 10 A metallic ring was first submerged in water and weighed against a mass of 10 g When the ring was submerged in oil of sp gr 0 8 the balancing weight had the mass of 13 g Calculate the true density of the ring material

Sir Ma am in Pascal s law it is being told that pressure app lied at any place in an enclosed fluid is transmitted with u ndiminished magnitude to every portions of fluid and acts normally to surface in contact with it Sir Ma am now my question is that what will be the proble m if the fluid is not enclosed

Three vessels placed on horizontal ground are shown in figure All three vessels are symmetric about the dotted line shown Which of the following are correct 11 C A B A if all the three vessels are filled with water upto dotted line then they pressure is same on the bottom surface B if all the three vessels are filled with equal volumes below dotted line with water and if base areas are same then equal pressure on the bottom surface C if all three vessels but below dotted line of same base area are filled with equal masses of three different liquids PA PB Pc on container due to liquid is same D in option C force on the base of vessel A is maximum

A metal sphere weighs 200 gram in air and 170 gm in water Then find the volume of cavity in cc in metal sphere If Pmetal 8gm c c Pwater 1m c c Answer

The density of liquid contained in the tank of area 0 5 m is 1200 Kg m It has a hole of area 1 cm near the bottom A load of 30 Kg is applied on the liquid at the top Find the velocity of efflux when the height of liquid level is 75 cm above the bottom g 10 m s 30Kg h A B C D 0 4 m s 8 m s 12 m s 16 m s 2 Correct Answer

3 A metal plate of area 10 cm rests on a layer a oil 6 mm thick A tangential force 102 N is applied on it to move it with a constant velocity of 6 cms The coefficient of viscosity of the liquid is 1 0 1 poise 2 0 5 poise 3 0 7 poise 4 0 9 poise

9 Two drops of equal radius coalesce to form bigger drop What is ratio of surface energy c bigger drop to a smaller one 1 21 2 1 2 1 1 3 22 3 1

A liquid mixture of volume V has two liquids as its ingredients with densities and B If density of the mixture is a then mass of the first liquid in mixture is 1 3 av o 1 B a a aV B o 2 4 av a B a B av 1 00 Plex

23 A spherical drop of water has 1 mm radius If the surface tension of water is 75 x 10 N m then difference of pressure between inside and outside of the drop is 1 35 N m 3 140 N m 2 70 N m 4 150 N m

A large vessel of height H is filled with a liquid of density p upto the brim A small hole of radius A is made at the side vertical face close to the base The horizontal force is required to stop the gushing of liquid is 1 2 pgH 3 pgHar m 2 pgH 4 come

3 A tank is filled with water to a height H A hole is made in one of the walls at a depth D below the water surface The distance x from the foot of the wall at which the stream of water coming out of the tank strikes the ground is given by 1 x 2 D H D 2 x 2 g 2 3 x 2 D H D 2 4 None of these 1 2 3 4 38 The with

al bed 3 Energy is neither liberated nor absorbed 4 Some mass is converted into energy 41 The radius of a soap bubble is r The surface tension of soap solution is S Keeping temperature constant the radius of the soap bubble is doubled The energy necessary for this will be 1 24 S 3 16 S 2 8 r S 4 12 S

31 A liquid flows in the tube from left to right as shown in figure A and A are the cross sections of the portions of the tube as shown The ratio of speed will be V V 1 3 A A A 2 4 A V P A A

4 All of these The terminal velocity of a small sized spherical body of radius r falling vertically in a viscous liquid is given by the proportionality 1 v 2 V

pressibility of liquid Two soap bubbles are connected by a tube as shown in figure What happens when stopper S is removed liquid lead 1 Size of bubble A increases 2 Size of bubble B decreases 3 Both bubble take the same size 4 Size of bubble A decreases and size of bubble B increases S B

13 A block of wood floats in water with t th of its volume submerged but it just floats in another liquid The density of liquid is in kg m 1 750 3 1000 2 800 4 1250

33 What will be the work done in increasing the radius of soap bubble from solution is T 1 3nr T 3 9 r T 2 4 30m T 12 r T 2 2 to 2r if surface tension of soap

3 May be zero 4 All of these Figure shows two containers P and Q with same base area A and each filled upto same height with same liquid Select the correct alternative P P 1 P Py 2 P Py 3 Py P 4 Cannot say Py Q

Figure shows a container filled with a liquid of density p Four points A B C and D lie on the diametrically opposite points of a circle as shown Points A and C lie on vertical line and points Band D lie on horizontal line The incorrect statement is PA PB Po Po are absolute pressure at the respective points A petitive Exams Mustpealin

EXERCISE An object of mass m is floating in a liquid of density a If the object is made up of density p then apparent weight of the object in the liquid is 2 mg 1 2 1 mg mal 1 2 4 Zero

A small spherical ball is released in a viscous liquid whose density is half that of density of the ball After attaining terminal speed ratio of work done by viscous force to work done by gravity on ball during a certain displacement is Question Type Single Correct Type 1 7 2 3 1 2 2 2

3 Two cylinders of same cross section and length L but made of two different materials of densities dy and d are cemented together to form a cylinder of length 2L The combination floats in a liquid of density d with a length L 2 above the surface of the liquid If d d then 3 3x d b d a d 4 b c 0 d d d 4

78 A wire frame ABCD has a soap film The wire BC can slide on the frame without friction and it is in equilibrium in the position shown in the figure Find m if T is the surface tension of the liquid a c 271 T1 A D B C b d TI g TI wwwww m

nderstand the previous explaination A drop of water of mass m and density p is placed between two well cleaned glass plates the distance between which is d What is the force of attraction between the plates T surface tension A B Tm 2pd C 4Tm pd 27m pd Tm D pd Your Answer D Correct Answer I Donorintion

A rigid ring A and a rigid thin disk B bo of same material when gently placed c just manage to float due to surface te shown in the figure Both the ring and have same radius What can you c about their masses thickness may be di 0 A B 1 Both have the same mass 2 Mass of the ring is half of that of 3 Mass of the ring is double to that of 4 More information is needed to

13 Atmospheric pressure is 1 0x105 N m and the density of air is 1 29 kg m If the density of air is constant as you get higher and higher the height of the atmosphere needed to produce this pressure is A 77000 m O B 10300 m O C 7900 m O D 1200 m

3 4 will fly up When water droplets merge to form a bigger 38 drop down on the floor of the hall 1 Energy is liberated 2 Energy is absorbed 3 Energy is neither liberated nor absorbed 4 Energy may either be liberated or absorbe donending on the nature of the liquid

4 Becomes zero Water is flowing through a long horizontal 3 tube Let P and P be the pressure at two point A and B of the tube then 1 P must be equal to P 2 P must be greater than P 65 P must be less than P 4 P P only if cross sectional area at A an

A ball is Pwater P Poil 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 oil 1 water 3 oil water 2 water 4 oil water Foil

An ice cube is suspended in vaccum in a gravity 37 free hall As ice melt it 1 Will retain its cubical shape 2 Will change its shape to spherical 3 Will fall down on the floor of the hall 4 will fly up bigge

Density of viscous fluid only For an aerofoil which of the following statement s is are correct 1 The orientation of the wings relative to flow direction causes the streamline II Flow speed on top is lower than that below it III Upward force resulting in dynamic lift of the wings 1 Only I 2 Only III

The three vessel shown in figure have same base area Equal volumes of a liquid are poured in the three vessel The force on the base will be VUU B A C 1 Maximum in vessel A 2 Maximum in vessel B 3 Maximum in vessel C 4 Equal in all the vessels

The pressure in a liquid at two points in the same horizontal plane are equal Consider an elevator accelerating upward and a ca accelerating on a horizontal road then the abo statement is correct for 1 The car only 2 The elevator only 3 Both of them 4 Neither of them levator aco

Equal masses of three liquids are kept in three 30 identical cylindrical vessels A B and C The densities are PA PB Pc respectively where PA PB PC then the force on the base will be 1 Maximum in vessel A 2 Maximum in vessel B 3 Maximum in vessel C 4 Fqual in all the vessels

A Beaker containing a liquid is kept inside a big 3 closed jar If the air inside the jar is continuously pumped out the pressure in the liquid near the bottom of the liquid will be 1 Increase 2 Decrease 3 Remain constant 1 First decrease and then increase

A space 2 5 mm wide between two large pla surfaces is filled with oil as shown in diagra Force required to drag a very thin plate of a of one side 0 5 m just midway of the surfac at a velocity of 0 5 m sec is 1 N The coeffici of viscosity in kg m sec is 2 5mm 1 1 x 10 11 25 mm F 2 2 5 x 10 2 0 35 x 10 3

ght of the liquid in the beaker We have three beakers A B and C containing 21 three different liquids They are stirred vigorously and placed on a table Then liquid which is 1 Most viscous comes to rest at the earliest 2 Most viscous comes to rest at the last 3 Most viscous slow down earliest but comes to rest at the last 4 All of them come to rest at the same time

ALLEN 13 Two identical air bubbles are rising in water If they coalesce under isothermal condition to form a single air bubble the combined air bubble would have 1 Higher excess pressure but smaller terminal velocity 2 Higher excess pressure and higher terminal velocity 3 Lower excess pressure and smaller terminal velocity 4 Lower excess pressu

15 Which of the following statement s is are 1 correct I Atoms or molecules in a fluid are arranged in a random manner II A fluid can withstand tangential or shearing stress for an indefinite period III A fluid has no definite shape of its own 1 Only I 2 Both I and III 3 Only III 4 All of these