# 4 FLUID STATICS AND DYNAMICS

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4. FLUID STATICS AND DYNAMICS
1)   The rain drops are in spherical shape due to
A)     Viscosity
B)     Surface tension
C)     thrust on drop
D)     residual pressure

2)   An iron needle floats on the surface of water. This phenomenon is attributed to
A)     upthrust of liquid
B)     Viscosity
C)     surface tension
D)     gravitational forces

3)   The excess pressure across the surface of a soap bubble of radius r(with σ as the
surface tension of soap solution)is
A)      A)  / r
B)      2 / r
C)      4 / r
D)      8 / r

4)   Two soap bubbles are blown simultaneously .In the first soap bubble, the excess
pressure is 4 times of second soap bubble. The ratio of radii of first to second
soap bubble is
A)      1:4
B)      2:1
C)      1:2
D)      4:1

5)   The property utilized in the manufacture of lead shots is
A)     specific weight of liquid lead
C)     specific gravity of liquid lead
D)     surface tension of liquid lead
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6)    A block of volume ‘V and of density σ b is placed in a liquid of density σ l (σ l > σ
b ), then block is moved upward due to buoyant force to a height ‘h’. The increase
in potential energy is
A)       σ b Vgh
B)       (σ b + σ l) Vgh
C)       (σ b - σ l) Vgh
D)       Zero

7)    Two small drops of mercury, each of radius r, form a single large drop. The ratio
of surface energy before and after this change is
A)     1:21/3
B)     21/3:1
C)     C ) 2:1
D)     1:2

8)    A wooden block is taken to the bottom of a deep, calm lake of water and then
released. It rises up with a
A)     constant acceleration
B)     decreasing acceleration
C)     constant velocity
D)     decreasing velocity

9)    A man in a lift is holding a can filled with water but having a hole in its bottom.
When will the drainage of water be maximum?
A)    When the lift is going up with acceleration
B)    when the lift is going down with acceleration
C)    When the lift is stationary
D)    when the lift goes down with uniform velocity

10)   In old age, arteries carrying blood in the human body, become narrow resulting in
an increase in the blood pressure. This follows from
A)      Pascal’s law
B)      Stoke’s law
C)      Bernoulli’s principle
D)      Archimedes principle

11)   Soap helps in better cleansing of clothes because
A)     it reduces the surface tension of solution
B)     it does not reduce the surface tension of solution
C)     it absorbs the dirt
D)     chemicals of soap change
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12)   If two soap bubbles of different radii are in communication with each other
A)      air flows from the larger bubble into the smaller one until the two bubbles
are of equal size
B)      the sizes of the bubbles remain unchanged
C)      air flows from the smaller bubble into the larger one and large bubble
grows at the expense of the smaller one
D)      air flows from the larger into the smaller bubble until the radius of the
smaller one becomes half that of the larger one

13)   More liquid rises in a thin tube because of
B)     larger value of surface tension
C)     smaller value of S.T

14)   The surface tension of soap solution is 25x10 -3Nm-1 . The excess pressure inside a
soap bubble of diameter 1 cm is
A)     10 Pa
B)     20 Pa
C)     5 Pa
D)     15 Pa

15)   Water rises in a capillary tube to a certain height such that the upward force due to
surface tension is balanced by 75 × 10-4 N force due to weight of the liquid. If the
surface tension of water is 6 × 10-2 Nm-1, the inner circumference of the capillary
must be
A)     1.25 × 10-2m
B)     0.50 × 10-2m
C)     6.5 × 10-2m
D)     12.5 × 10-2 m

16)   When a soap bubble is charged
A)    it contracts
B)    it expands
C)    it does not undergo any change in size
D)    it disappears

17)   A drop of oil is placed on the surface of water. Which of the following statements
is correct?
A)     it will remain on it as a sphere
B)     it will spread as a thin layer
C)     it will partly changed to spherical droplets and partly as thin film
D)     it will float as a distorted drop on the water surface
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18)   Small droplets of liquid are usually more spherical in shape than larger drops of
the same liquid because
A)     force of surface tension is equal and opposite to the force of gravity
B)     force of surface tension predominates the force of gravity
C)     force of gravity predominates the force of surface tension
D)     force of gravity and force of surface tension act in the same direction and
are equal

19)   Water rises to a height of 16.3 cm in a capillary of height 18 cm above the water
level. If the tube is suddenly cut at a height of 12 cm
A)       water will come as a fountain from the capillary tube
B)       water will stay at a height of 12 cm in the capillary tube
C)       the height of the water in the capillary will be 10.3 cm
D)       water will flow down the sides of the capillary tube

20)   A soap bubble has radius r and the surface tension of the soap film is T . The
energy needed to double the diameter of the bubble without change of
temperature is
A)     4 r 2T
B)     2  r2 T
C)     12  r2T
D)     24  r2T

21)   A hollow sphere has a small hole in it. On lowering the sphere in a tank of water
to a depth of 40 cm below the surface it is observed that water enters into the
hollow sphere. Surface tension of water is 7 × 10-3 Nm-1. The diameter of the hole
is
A)      1/7 mm
B)      1/14 mm
C)      1/21 mm
D)      1/28 mm

22)   A liquid drop of radius R is broken up into N small droplets. The work done is
proportional to
A)     N
B)     B N-2/3
C)     C. N-1/3
D)     D. N-0.5
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23)   An air bubble of radius r is formed inside a tank of water of depth h. The
atmospheric pressure is equal to a water column of height H. the pressure inside
the bubble is
A)      A.H + h
B)      H + h + 2T/r
C)      H + h + 4T/r
D)      H + h + T/r
(T is surface tension of water)

24)   A liquid film is formed over a frame ABCD as shown in the figure. Wire CD can
slide without friction. The mass to be hung from CD to keep it in equilibrium is

A)     Tl/g
B)     .2Tl/g
C)     4Tl/g
D)     T ×l

25)   It is easier to spray water to which soap is added, because
A)       addition of soap to water decreases surface tension of water
B)       addition of soap to water increases surface tension of water
C)       addition of soap to water makes surface tension of water zero
D)       addition of soap to water increases its density

26)   A capillary tube remains dipped in a water container, so that loss in weight of the
capillary tube is
A)      equal to the upward buoyant force
B)      less than the upward buoyant force
C)      more than the upward buoyant force
D)      half of the buoyant force
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27)   One thousand small water droplets of equal size combine to form a big drop. The
ratio of the final surface energy to the total initial surface energy is
A)      10:1
B)      1:10
C)      1000:1
D)      1:1000

28)   The unit of surface tension in M.K.S units is given by
A)     Dynes per cm2
B)     dynes per cm
C)     Newtons per meter
D)     Newtons per metre2

29)   What will be the height of a liquid column in a capillary tube on the surface of
the moon?
A)     six times that on earth's surface
B)     1/6th of what was on earth's surface
C)     it will remain unchanged
D)     zero

30)   Two match sticks are laid side by side on the surface of water. When a drop of
light oil on the end of a third match stick is touched to the surface film between
the two floating sticks , the two match sticks
A)      will move apart rapidly
B)      will remain as they are
C)      will come closer
D)      will be joined

31)   A water drop of radius 1 mm is broken into 106 equal droplets. How much work is
done in it if the temperature remains constant? Surface tension of water = 0.072
J/m2
A)     8.95 × 10-3 J
B)     8.95 × 10-5 J
C)     8.95 × 10-7 J
D)     8.95 × 10-9 J

32)   Soldering of two metals possible because of the property of
A)     viscosity
B)     surface tension
C)     osmosis
D)     cohesion
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33)   When the adhesive force in the case of liquid and glass is greater than the
cohesive forces between the liquid molecules, the shape of the meniscus of liquid
in a capillary tube is
A) Plane
B) concave
C) Convex
D) circular

34)   S.T of water is 5 N/m. If a film is formed on a ring of area 0.02 m2, then its
surface energy is
A)      5 × 10-2 joule
B)      2.5 × 10-2 joule
C)      2 × 10-1 joule
D)      3 × 10-1 joule

35)   If the work done in blowing a bubble of volume V is W, then the work done in
blowing a soap bubble of volume 2V will be
A)      W
B)      2W
C)        2W
3
D)        4W

36)   The pressure inside two soap bubbles is 1.01 and 1.02 atmosphere respectively.
The ratio of their volumes is
A)     102:101
B)     (102)3 : (101)3
C)     8:1
D)     2:1

37)   The surface tension of soap is 0.475 × 10-2 N/m . The work done in blowing a
soap bubble of radius 2.0 cm is
A)     7.6 × 10-6 π joule
B)     15.2 × 10-6 π joule
C)     1.9 × 10-6 π joule
D)     D )1 × 10-4 π joule

38)   A soap bubble of diameter 8 cm is formed in air. The surface tension of liquid is
30 dyne/cm. The excess pressure inside the soap bubble is
A)     150 dyne/cm2
B)     30.0 dyne/cm2
C)     3 × 10-3 dyne/cm2
D)     12 dyne/cm2
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39)   Two tubes of the same material but of different radii are dipped in a liquid. The
height to which a liquid rises in one tube is 2.2cm and in the other is 6.6 cm. The
A)      9 :1
B)      1:9
C)      3:1
D)      1:3

40)   A large air bubble of radius r rises from the bottom of a lake to the surface. The
depth of the lake is 7H. If the atmospheric pressure is equal to that of water of
height H, the radius of the bubble is
A)     r
B)     2r
C)     3r
D)     8r

41)   A raft of wood of density 600kg/m3 and mass 120 kg floats in water. How much
weight can be put on the raft to make it just sink?
A)      200kg
B)      40kg
C)      120kg
D)      80kg

42)   If a block of iron (density 5gm/cm3) of size 5 cm × 5 cm × 5 cm was weighed
whilst completely submerged in water, what would have been its apparent
weight?
(density of water = 1 gm/cm3)
A)      5 × 5 × 5 × 5gm
B)      4 × 4 × 4 × 5 gm
C)      3 × 5 × 5 × 5 gm
D)      4 × 5 × 5 × 5 gm

43)   A boy is carrying a bucket of water in one hand with a 0.05 kg cork piece in it.
After sometime he takes out the cork piece and holds it in the other hand. The
boy will carry
D)      Either less or more load depending on the density of plastic.
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44)   A beaker is partly filled with water, the beaker and the contents have a mass of 50
gm. A piece of wood having a volume of 5 cc. is floated in the beaker. The
density of wood is 0.8 g/cc. the mass of the beaker and its contents is
A)     50 g
B)     54g
C)     46 g
D)     56.25 g

45)   A bird, resting on the floor of an airtight box, which is being carried by a boy,
starts flying. The boy will feel that the box
A)       is now heavier
B)       is now lighter
C)       shows no change in weight
D)       lighter in the beginning and heavier afterwards

46)   A cube of size 10 cm is floating in equilibrium in a tank of water. When a mass of
10 gm is placed on the cube, the depth of the cube inside the water increases by
(g = 10 ms-2 density of water = 103 kg m-3)
A)      0.1 mm
B)      1mm
C)      1 cm
D)      0.1 m

47)   A wooden cube just floats inside water when a 200gm mass is placed on it. When
the mass is removed, the cube is 2 cm above the water level. The size of the cube
is
A)     5 cm
B)     10 cm
C)     15 cm
D)     20 cm

48)   Pressure applied to an enclosed fluid is
A)    increased and applied to every part of the fluid
B)    diminished and transmitted to the wall of the container
C)    increased in proportion to the mass of the fluid and then transmitted
D)    transmitted unchanged to every portion of the fluid and walls of the
containing vessel.

49)   A parrot is in a wire case, which is hanging from a spring balance. Initially
the parrot sits in the cage and in the second instant the parrot flies inside the cage
A)     the reading of the balance will be greater when the parrot files in the cage
B)     the reading of the balance will be lesser when the parrot files in the cage
C)     the reading will remain unchanged
D)     None of the above
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50)   If there would be smaller gravitational effects, which of the following forces do
you think would alter in some respect?
A)      Viscous forces
B)      Buoyant forces
C)      Nuclear forces
D)      Electrostatic forces

51)   Two stretched membrances of area 2m2 and 3m2 are placed in a liquid at the same
depth. The ratio of the pressures on them is
A)     1:1
B)     2:3
C)       2 : 3
D)      2
2 : 32

52)   If you float on your back on water, your weight is
A)      Zero
B)      equal to your normal weight
C)      half to your normal weight
D)      greater than the weight of water you displace

53)   The height of mercury column in a simple barometer is h. As tube is inclined to
the vertical at an angle  . The length of the mercury column along the length of
the tube is l, then
A)      1=h
B)      1 = h/cos 
C)      1 = h cos 
D)      1 = h sin 

54)   Find the lifting force of a 4 kg cork life belt in sea water if the density of cork and
sea water are 0.2 × 103 kg/m3 and 1.03 × 103 kg/m3 respectively.
A)     163 N
B)     273 N
C)     119 N
D)     289 N

55)   A cylindrical vessel is filled with equal mass of mercury and water. The over all
height of the two layers is 43.8 cm. Relative density of mercury is 13.6. Then the
pressure of the liquid on the bottom of the vessel is
A)      3 cm of Hg
B)      6 cm of Hg
C)      1.5 cm of Hg
D)      16.6 cm of Hg
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56)   Two bodies are in equilibrium when suspended in water from the arms of a
balance. The mass of one body is 36 gm and its density is 9 gm/cc. If the mass of
the other is 48 gm, its density in gm/cc is
A)      4/3
B)      3/2
C)      3
D)      5

57)   Three liquids of densities d, 2d and 3 d are mixed in equal volumes. Then the
density of mixture is
A)      d
B)      2d
C)      3d
D)      5d

58)   Three liquids of densities d, 2d and 3d are mixed in equals proportions of weights.
The relative density of the mixture is
A)      11/7d
B)      18/11d
C)      13/9d
D)      23/18d

59)   A piece of metal of specific gravity 3.4 floats in mercury of specific gravity 13.6.
What fraction of its volume is under mercury?
A)     0.25
B)     0.50
C)     0.75
D)     0.80

60)   A capillary tube of radius r is placed in a liquid. If the angle of contact is  , the
radius of curvature R of the meniscus in the capillary is
A)      r
B)      r sin
r
C)
cos 
D)      r cos 
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61)   Water flows steadily through a horizontal pipe of a variable cross-section. If the
pressure of water is P at a point where the velocity of flow is  , what is the
pressure at another point where the velocity of flow is 2  ;  being the density of
water?
3       2
A)     P-      
2
3      2
B)     P+       
2

C)     P -2   2
D)     P + 2  2

62)    The cylindrical tube of a spray pump has a radius R, one end of which has n fine
holes, each of radius r. If the speed of flow of the liquid in the tube is V, the speed
of ejection of the liquid through the holes is
1/ 2
V    R
A)            
n    r
V    R
B)            
n    r
3/ 2
V R
C)         
n r
2
V R
D)         
n r

63)   In a test experiment on a model aeroplane in a wind tunnel, the flow speeds on the
lower and upper surfaces of the wings are  and 2  respectively. If the
density of air is  and the surface area of the wings is A, the dynamic lift on the
wing is given by
1
A)             2A
2
1
B)          2 A
2
C)          2  2A

D)     2  2A
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64)   Water is flowing through a tube of radius r with a speed  . If this tube is joined to
another tube of radius r/2, what is the speed of water in the second tube?

A)
4
B)      
2
C)     2
D)     4

65)    A liquid flows through a pipe of varying diameter. The velocity of the liquid is
2ms-1 at a point where the diameter is 6cm. The velocity of the liquid at a point
where the diameter is 3 cm will be
A)      1 ms-1
B)      4ms-1
C)      8ms-1
D)      16ms-1

66)   Which one of the following statements is correct for a fluid passing through the
narrow part of non-uniform pipe.
A)     its velocity and pressure both increase
B)     its velocity and pressure both decrease
C)     its velocity decreases but its pressure increases
D)     its velocity increases but its pressure decreases

67)   Water from a tap emerges vertically downwards with an initial speed of 1.0 ms-1.
The cross-sectional area of tap is 10-4 m2. Assume that the pressure is constant
throughout the stream of the water and that the flow is steady. The cross –
sectional area of the stream 0.15 m below the tap is (take g =10 ms-2)
A)     5.0  10-4 m2
B)     1.0  10-5 m2
C)     5.0  10-5 m2
D)     2.0  10-5 m2

68)   A large open tank has two holes in the wall. One is a square hole of side L at a
depth y from the top and the other is a circular hole of radius R at a depth 4y from
the top. When the tank is completely filled with water, the quantities of water
flowing out per second from both the holes are the same. Then R is equal to
L
A)
2
B)      2     L
C)      L
L
D)
2
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69)   A cylindrical jar of cross-sectional area 0.01m2 is filled with water to a height of
50 cm. It carries a tight-fitting piston of negligible mass. What is the pressure at
the bottom of the jar when mass of 1 kg is placed on the piston? Take g = 10ms-2
A)      105 pa
B)      6000 pa
C)      5000 pa
D)      1000 pa

70)   Two vessels A and B of different shapes have the same base area and are filled
with water up to the same height h. The force exerted by water on the base is FA
for vessel A and FB for vessel B. The respective weights of the vessels are WA and
WB. Then
A)      FA > FB; WA > WB
B)      FA = FB; WA>WB
C)      FA = FB; WA<WB
D)      FA>FB; WA=WB

71)   A tank with a square base of area 2.0 m2 is divided into two compartments by a
vertical partition in the middle. There is a small hinged door of face area 20cm2 at
the bottom of the partition. Water is filled in one compartment and an acid, of
relative density 1.5, in the other, both to a height of 4m. If g = 10 ms-2, the force
necessary to keep the door closed is
A)      10 N
B)      20 N
C)      40 N
D)      80N
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72)   A U-tube contains water and oil separated by mercury. The mercury columns in
the two arms are at the same level with 10 cm of water in one arm and 12.5 cm of
oil in the other, as shown in figure
The relative density of oil is

A)     0.8
B)     1.0
C)     1.25
D)     2.0

73)   In Q. 72, 15 cm column more of water and oil each are poured into the respective
arms of the U-tube. If the relative density of mercury is K, the difference in the
levels of mercury in the two arms will be
1
A)         cm
K
2
B)         cm
K
3
C)         cm
K
4
D)         cm
K

74)   A block of wood float in a liquid in a beaker with 3/4ths of its volume submerged
under the liquid. If the beaker is placed in an enclosure that is falling freely under
gravity, the block will
A)      float with ¾ths of its volume submerged
B)      float completely submerged
C)      float with any fraction of its volume submerged
D)      sink to the bottom.
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75)   A cubical block of steel of each side equal to l is floating on mercury in a vessel.
The densities of steel and mercury are s and m. The height of the block above
the mercury level is given by
     
A)     l 1  s 

    m 
      s   
B)     l 1 
           

      m   
      m   
C)     l 1 
           

      s   
      m   
D)     l 1 
           

      s   

76)   A spring balance reads 10kg when a bucket of water is suspended from it. What
will be the reading of the balance when an iron piece of mass 7.2 kg suspended by
a string is immersed with half its volume inside the water in the bucket? Relative
density of iron is 7.2.
A)      10kg
B)      10.5kg
C)      13.6 kg
D)      17.2 kg

77)   A body floats in water with 40% of its volume outside water. When the same
body floats in oil, 60% of its volume remains outside oil. The relative density of
oil is
A)     0.9
B)     1.2
C)     1.5
D)     1.8

78)   The relative density of ice is 0.9 and that of sea water is 1.125. What fraction of
the whole volume of an iceberg appears above the surface of the sea?
A)     1/5
B)     (b)2/5
C)     3/5
D)     4/5
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79)   A cube of wood supporting a mass of 200 g just floats in water. When the mass is
removed, the cube rises by 2 cm. What is the size of the cube?
A)     6 cm
B)     8cm
C)     10 cm
D)     12 cm

80)   A boat carrying a number of large stones is floating in a water tank. What will
happen to the water level if the stones are unloaded into the water? The water
level
A)     remains unchanged
B)     rises
C)     falls
D)     rises till half the number of stones are unloaded and then begins to fall

81)   A piece of ice, with a stone frozen inside it, is floating in water contained in a
beaker. When the ice melts, the level of water in the beaker
A)     rises
B)     falls
C)     remains unchanged
D)     falls at first and then rises to the same height as before

82)   A piece of copper having an internal cavity, weighs 264 g in air and 221 g in
water. The density of copper is 8.8 g cm-3. What is the volume of the cavity?
A)     12cm3
B)     13 cm3
C)     14 cm3
D)     15 cm3

83)   A stone of relative density K is released from rest on the surface of a lake. If
viscous effects are ignored, the stone sinks in water with an acceleration of
A)     g (1 – K)
B)     g(1 + K)
 1
C)     g 1  
 k
 1
D)     g 1  
 k
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84)     Two identical cylindrical vessels, each of base area A, have their bases at the
same horizontal level. They contain liquid of density  . In one vessel the height
of the liquid is h1 and in the other h2 (> h1). When the two vessels are connected,
the work done by gravity in equalizing the levels is
A)       2  Ag(h2 – h1)2
B)        Ag (h2 – h1)2
1
C)         Ag (h2 – h1)2
2
1
D)         Ag (h2 – h1)2
4

85) A cylindrical jar has radius r .To what height h should it be filled with a liquid so
that the force exerted by the liquid on the sides of the jar equals the force exerted on
the bottom?
r
A)       h=
2
B)       h=r
C)       h = 2r
D)       h = 4r

86) The work done to break up a drop of a liquid of radius R and surface tension  into
eight droplets, all of the same size, is
A)      4 π R2
B)      2 π R2
1
C)         π R2
2
1
D)         π R2
4

87) The excess pressure across a soap bubble of radius r is p =4/r, where  is the
surface tension of soap solution. What is the excess pressure across an air bubble of
the same radius r formed inside a container of soap solution?

A)
r
2
B)
r
4
C)
r
8
D)
r
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88)   In Q.87, if the air bubble is formed at a depth h inside the container of soap
solution of density  , the total pressure inside the bubble is (here P0 denotes the
atmospheric pressure)
2
A)           + hg 
r
2
B)           - hg 
r
2
C)      P0 +      + hg 
r
2
D)      P0 +       - hg 
r

89)   Tiny insects can float and walk on the surface of water due to
A)     buoyancy alone
B)     surface tension alone
C)     both buoyancy and surface tension
D)     neither buoyancy nor surface tension

90)   A small drop of water of surface tension  is squeezed between two clean glass
plates so that a thin layer of thickness d and area A is formed between them. If the
angle of contact is zero, the force required to pull the plates apart is
A
A)
d
2A
B)
d
4A
C)
d
8A
D)
d

91)    A small spherical ball of density  is gently released in a liquid of density 
( ). The initial acceleration of the free fall of the ball will be
   
A)        g
       
       
   
B)             g
  
   
C)      
  g  
       
D)      g
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92)    The time period of a simple pendulum is T. The pendulum is oscillated with its
bob immersed in a liquid of density  . If the density of the bob is  and viscous
effect is neglected, the time period of the pendulum will be
1
       2
A)      
      T

        
1
       2
B)      
      T

        
1
              2
C)                         T
       
1
 2
D)        T

 

93)   A wooden block of mass m and density  is tied to a string; the other end of the
string is fixed to the bottom of a tank. The tank is filled with a liquid of density 
with  > What is the tension in the string?
   
A)               mg
  
   
B)       
   mg
       
mg
C)

mg
D)


94)   Equal masses of two substances of densities 1 and 2 are mixed together. The
density of the mixture would be
1
A)         (1 + 2)
2
B)        1  2
1 2
C)
( 1   2)
2 1 2
D)
( 1   2)
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95)   Equal volumes of two substances of densities 1 and 2are mixed together. The
density of the mixture would be
1
A)         (1 + 2)
2
B)      (1 + 2)
C)        1  2
1 2
D)
( 1   2)

96)    A capillary tube of radius r is immersed in water and water rises in it to a height
h. The mass of water in the capillary tube is 5 g . Another capillary tube of radius
2r is immersed in water . The mass of water that will rise in this tube is
A)      2.5 g
B)      5.0 g
C)      10 g
D)      20 g

97)   In a surface tension experiment with a capillary tube, water rises upto 0.1 m. If the
same experiment is repeated in an artificial satellite, which is revolving round the
earth, water will rise in the capillary tube upto a height of
A)      0.1 m
B)      0.2 m
C)      0.98 m
D)      full length of the capillary tube.

98)    A concrete sphere of radius R has a cavity of radius r which is packed with
sawdust. The relative densities of concrete and sawdust are 2.4 and 0.3
respectively. For this sphere to float with its entire volume submerged under
water, the ratio of the mass of concrete to the mass of sawdust will be
A)      8
B)      4
C)      3
D)      Zero

99)   A closed compartment containing gas is moving with some acceleration in a
horizontal direction. Neglecting the effect of gravity, the pressure in the
compartment will be
A)     same every where
B)     lower in the front side
C)     lower in the rear side
D)     lower in the upper side
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100)   A vessel contains oil(density 0.8 g cm-3) over mercury ( density 13.6 g cm-3).
A homogeneous sphere floats with half volume immersed in mercury and the
other half in oil. The density of the material of the sphere in g cm-3 is
A)     3.3
B)     6.4
C)     7.2
D)     12.8

101)    A drop of water breaks into two droplets of equal size. Then which of the
following statements is correct?
A)     the sum of temperatures of two droplets is equal to the original
temperature
B)     The sum of masses of two droplets is equal to the mass of the original
drop
C)     The sum of radii of two droplets is equal to the radius of the original drop
D)     The sum of surface areas of two drops is equal to surface area of the
original drop

102)   A liquid does not wet the surface of a solid if the angle of contact is
A)     zero
B)     <90o
C)     > 90o
D)     of any value

103)   The angle of contact of mercury - glass surface is
A)     8o
B)     90o
C)     0o
D)     135o

104) When two tubes of different diameters are dipped vertically, the rise of liquid is
A) same in both tubes
B) more in tube of larger diameter
C) more in tube of smaller diameter
D) none of these

105)   The surface tension of a liquid with increase of temperature generally
A) increases
B) decreases
C) remains constant
D) decreases up to 100oC and then increases
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106)   When the temperature increases, the angle of contact of a liquid will
A) increase
B) decrease
C) remain unchanged
D) first increase and then decrease

107)   A water proofing agent will change the angle of contact
A) from an obtuse to acute value
B) from an acute to obtuse value
C) from acute to  / 2
D) from obtuse to  / 2

108)   One end of a towel dips into a bucket full of water and the other end hangs over
the bucket. It is found that after some time the whole towel becomes wet. This
happens because
A) viscosity of water is high
B) of capillary action of cotton threads
C) of gravitational force
D) of evaporation of water

109)   The pressure just below the meniscus of water
A) is greater than just above it
B) is less than just above it
C) is same as just above it
D) is always equal to atmospheric pressure

110)   The figure below represents three soap bubbles A, B and C prepared by blowing
the capillary tube with stop cocks S, S1, S2 and S3. With stop-cock S closed and
S1, S2, S3 opened

A)   B will start collapsing with volumes of A and C increasing
B)   C will start collapsing with volumes of A and B increasing
C)   Volumes of A, B, and C will becomes equal at equilibrium
D)   C and A will both start collapsing with volume of B increasing
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111)   Two soap bubbles have radii in the ratio 2:1. What is the ratio of excess pressure
inside them?
A) 1:2
B) 2:1
C) 1:8
D) 8:1

112)    A soap bubble (surface tension= 30 10-3 N-m-1) has radius 2 cm. The work done
A) 0
B) 21.1355  10-4 J
C) 12.261  10-4 J
D) 4.043  10-4 J

113)    If the work done in blowing a bubble of radius R is W, then the work done in
blowing a bubble of radius 2R from that solution is
A) W/2
B) 2 W
C) 4W
D) 21/3 W

114)    A capillary tube of radius r can support a liquid of weight 6.28  10-4 N. If the
surface tension of the liquid is 5 x 10-2 N/m, the radius of the capillary must be
A) 2.5  10-4 m
B) 1.5  10-3 m
C) 2.0  10-4 m
D) 2.0  10-3 m

115)    The amount of work done in increasing the size of a soap film 10 cm  6 cm to
10 cm  10 cm is (surface tension T = 0.030 N/m)
A)     2.4 x 1o-2 J
B)     2.4 x 10-4 J
C)      4.2 x 10-2 J
D)     4.2 x 10-4 J

116)   Which one of the following would a hydrogen balloon find easiest to lift?
A)    1 kg of steel
B)    1 kg of water
C)    1 kg of lightly packed feathers
D)    1 kg of ice
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117)   Bernoulli's theorem is based on
A)    conservation of momentum
B)    conservation of energy
C)    mass-energy equivalence
D)    conservation of mass

118)    If two ping-pong balls are suspended near each other and a fast stream of air is
produced within the space between the balls, the balls will
A) come closer
B) move farther
C) remain in original position
D) fall down

119)    A fast train goes past a wayside station platform at high speed. A person standing
at the edge of the platform tends to be
A)      pulled towards the train
B)      pushed away from the train
C)      affected only if the train's speed is more than the speed of sound
D)      unaffected by the ongoing train

120)   Paint-gun is an application of
A)     Bernoulli's theorem
B)     Archimedes principle
C)     Newton’s law of motion
D)     Boyle’s law

121)    A hole is near the bottom of a tank. The volume of liquid emerging from the hole
does not depend upon
A)     height of liquid level above hole
B)     area of hole
C)     density of liquid
D)     gravitational acceleration

122)   An application of Bernoulli’s equation for fluid flow is found in the
A)    dynamic lift of an aeroplane
B)    viscosity meter
C)    hydraulic press
D)    capillary rise
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123)    A horizontal pipe line carries water in a stream line flow. At a point along the
pipe where cross sectional area is 10 cm2, the water velocity is 1 m/s and the
pressure is 2000 Pa. The pressure of water at another point where the cross
sectional area is 5 cm2 is (density of water =103 kg-m-3)
A)     1000 Pa
B)     500 Pa
C)     3500 Pa
D)     1625 Pa

124)    A body is just floating in a liquid (their densities are equal). If the body is slightly
pressed and released it will
A)     start oscillating
B)     sink to the bottom
C)     come back to the same position immediately
D)     come back to the same position slowly

125)     In order that a floating object remain in a stable equilibrium, its center of
buoyancy should be
A)      vertically above its center of gravity
B)      below its center of gravity
C)      horizontally in line with its centre of gravity
D)      may be anywhere

126)   The principle of working of a hydraulic press is based upon
A)     Boyle's Law
B)     Pascal's law
C)     Dalton’s law of partial pressures
D)     Newton’s law of gravitation

127)   A cylinder is filled with water of density  upto a height h. If the beaker is at rest,
the average pressure at the walls is
A)     0
B)     hg
C)     hg/2
D)     hg/6

128)   A beaker has oil of relative density 1.2 upto a height of 3 cm. On top of the oil is a
water column of height 10 cm. If the relative density of mercury is 13.6 , the
pressure at the bottom of the beaker is
A)     1 cm of Hg
B)     10 cm of Hg
C)     15 cm of Hg
D)     25 cm of Hg
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129)   A large piece of ice is floating in a jar containing water. When the ice melts, the
level of water
A)      rises
B)      falls
C)      remains unchanged
D)      rises or falls depending upon the size of piece

130) A boy is carrying a bucket of water in one hand and a piece of plastic in the other.
After transferring the plastic piece to the bucket (in which it floats) the boy will
carry
C)      either less or more load depending on the density of plastic

131)   In a satellite orbiting around the earth, a coin is dropped in a beaker of water and
released. It will
A)      rise
B)      sink
C)      remain where left
D)      oscillate

132)   A body tied to a string is suspended in a beaker full of water. The system is
allowed to fall freely. Then
A)     Tension is equal to weight of body
B)     Tension is zero and Archimedes law holds good
C)     Tension is zero and Archimedes law is not valid
D)     Tension in string is neither zero nor equal to mg but Archimedes law holds

133)   A body floats in a liquid contained in a beaker. The whole system as shown below
in the figure falls freely under gravity. The upthrust on the body due to liquid is

A)      Zero
B)      equal to weight of liquid displaced
C)      equal to weight of the body in air
D)      equal to weight of immersed portion of the body
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134)   A man is sitting in a boat which is floating on a pond. If the man drinks some
water from the pond, the level of the water in the pond
A)      decreases
B)      increases
C)      remains unchanged
D)      may decrease or increase depending on the weight of man

135)   A cubical vessel of height 1 m is full of water. The work done in pumping water
out of the vessel is
A)      49 J
B)      98 J
C)      4900 J
D)      9800 J

136)   A block of ice is floating in a liquid of specific gravity 1.2 contained in a beaker.
When the ice melts completely, the level of liquid in the vessel
A)     Rises
B)     Falls
C)     remains unchanged
D)     first rises and then falls

137)   A body floats with one-third of its volume outside water and three-fourth of its
volume outside another liquid. The density of the other liquid is
A)    9/4 g/cm3
B)    4.9 g/cm3
C)    8/3 g/cm3
D)    3/8 g/cm3

138)   A body of volume 100 cm3 is immersed completely in water contained in a jar.
The weight of the water and jar before immersion of the body was 700 gm. After
immersion the weight of the water and jar will be
A)    700 g
B)    500gm
C)    100 gm
D)    800 gm

139)   A block of steel of size 5 cm  5 cm  5 cm is weighed in water. If the relative
density of steel is 7 its apparent weight is
A)     6555g
B)     4447g
C)     4446g
D)     5557g
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140)   The spring balance A reads 2 kg with a block m suspended from it. A balance B
reads 5 kg when a beaker with liquid is put on the pan of the balance. The two
balances are now so arranged that the hanging mass is inside the liquid in the
beaker as shown in the figure. In this situation

A)      the balance A will read more than 2 kg
B)      the balance B will read less than 5 kg
C)      the balance A will read less than 2 kg and B will read more than 5kg
D)      the balance A will B will read 2 kg and 5 kg respectively

141)   What   is the apparent weight of wood floating in water if it weighs 100 g in air?
A)       200 g
B)       400 g
C)       100 g
D)       zero

142)   A drop of water breaks into two drops. In this process
A)     energy is evolved
B)     energy is absorbed
C)     no energy is evolved
D)     no energy is absorbed

143)   The radius of a spherical soap bubble is 0.5 mm. If the surface tension of the soap
solution be 30 dyne/cm, the excess pressure is
A)      1500 dyne/cm2
B)      1000 dyne/cm2
C)      2400 dyne/cm2
D)      1200 dyne/cm2
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144)   A vessel has a small hole at the bottom. Its radius is 0.4 mm. The height to which
water can be put inside the vessel without any leakage (surface tension =72
dyne/cm, g =9.8 m/s2) will be
A)     3.67 cm
B)     0.367 cm
C)     0.0367 cm
D)     zero

145)   When a capillary tube is dipped in water, it rises in the tube upto 6 cm. If this
experiment is repeated on the moon, water will rise upto
A)     same height
B)     1 cm
C)     2 cm
D)     36 cm

146)   The reading of a pressure meter attached to a closed water pipe is 3.5  105 N/m 2.
On opening the valve, the reading of the pressure meter is reduced to 3  105
N/m2. Calculate the speed of water flowing in the pipe
A)     10m/s
B)     20 m/s
C)     30 m/s
D)     40 m/s

147)   An iceberg is floating partially immersed in sea water. The density of sea water is
1.03 gm/cm3 and that of ice is 0.92 g/cm3. The fraction of the total volume of the
ice berg above the level of sea water is
A)      8%
B)      11%
C)      34 %
D)      89%

148)   The work done to get ‘n’ smaller equal size spherical drops from a bigger size
spherical drop of water is proportional to
A)     1/n2/3-1
B)     1/n1/3-1
C)     n1/3-1
D)     n4/3 -1

149)   Two soap bubbles, each with a radius r coalesce in a vacuum under isothermal
conditions to form a bigger bubble of radius R. Then R is equal to
A)     2-1/2 r
B)     21/3r
C)     21/2 r
D)     2r
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150)   A boat having a length 3 m and breadth 2 m is floating on a lake. The boat sinks
by 1 cm when a man gets on it. The mass of the man is
A)     60 kg
B)     72 kg
C)     12 kg
D)     128 kg
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4. FLUID STATICS AND DYNAMICS

1         B                               41         D
2         C                               42         D
3         C                               43         C
4         A                               44         B
5         D                               45         C
6         C                               46         B
7         A                               47         B
8         A                               48         D
9         A                               49         B
10         A                               50         B
11         A                               51         A
12         C                               52         A
13         D                               53         B
14         B                               54         A
15         D                               55         B
16         B                               56         C
17         B                               57         B
18         B                               58         B
19         D                               59         A
20         D                               60         C
21         B                               61         A
22         C                               62         D
23         B                               63         B
24         B                               64         D
25         A                               65         C
26         B                               66         D
27         B                               67         C
28         C                               68         A
29         A                               69         B
30         A                               70         B
31         B                               71         C
32         D                               72         A
33         B                               73         C
34         C                               74         C
35         D                               75         A
36         C                               76         B
37         B                               77         C
38         B                               78         A
39         C                               79         C
40         B                               80         C
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81         B                               116        C
82         B                               117        B
83         C                               118        A
84         D                               119        A
85         B                               120        A
86         A                               121        C
87         B                               122        A
88         C                               123        B
89         C                               124        B
90         B                               125        A
91         C                               126        B
92         A                               127        C
93         B                               128        A
94         D                               129        B
95         A                               130        A
96         C                               131        C
97         D                               132        C
98         B                               133        A
99         B                               134        C
100        C                               135        C
101        B                               136        A
102        C                               137        C
103        D                               138        D
104        C                               139        A
105        B                               140        C
106        B                               141        D
107        B                               142        B
108        B                               143        C
109        B                               144        A
110        D                               145        D
111        A                               146        A
112        D                               147        B
113        C                               148        C
114        D                               149        C
115        B                               150        A
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