JEE Questions for Physics Mechanical Properties Of Fluids Quiz 13 - MCQExams.com

Assertion The shape of an automobile is so designed that its front resembles the stream line pattern of the fluid through which it moves.
Reason The resistance offered by the fluid is maximum.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion The size of the needle of a syringe controls flow rate better than the thumb pressure exerted by a doctor while administering an injection .
Reason Flow rate is independent of pressure exerted by the thumb of the doctor.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion A fluid flowing out of a small hole in a vessel apply a backward thrust on the vessel
Reason According to equation of continuity, the product of area and velocity remain constant .
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion For a floating body to be in stable equilibrium, its centre of buoyancy must be located above the centre of gravity
Reason The torque produced by the weight of the body and the upthrust will restore body back to its normal position, after the body is disturbed.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If Assertion is true but Reason is false.
  • If Assertion is false but Reason is true.
Assertion In taking into account the fact that any object which floats must have an average density less than that of water, during world war I, a number of cargo vessels are made of concrete.
Reason Concrete cargo vessels were filled with air.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion A thin stainless steel needle can lay floating on a still water surface.
Reason Any object floats when the buoyancy force balances the weight of the object.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Aeroplanes are made to run on the runway before take off, so that they acquire the necessary lift.
Reason According to Bernoull\'s theorem, as velocity increases pressure decreases and viceversa.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Sudden fall of pressure at a place indicates storm.
Reason Air flows from higher pressure to lower pressure
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Machine parts are jammed in winter .
Reason The viscosity of lubricant used in machine parts increase at low temperature.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion When two boats sail parallel in the same direction and close to each other, they are pulled towards each other.
Reason The viscous drag on a spherical body moving with speed v is proportional to v.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion A rain drop after falling through some height attains a constant velocity
Reason At constant velocity, the viscous drag is just equal to its weight.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Railway tracks are laid on small sized wooden sleepers
Reason Small sized wooden sleepers are used so that rails exert more pressure on the railway track. Due to which rail does not leave the track.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Terminal velocity is same as the critical velocity
Reason The constant velocity of fall of a body through a viscous fluid is called terminal velocity.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
A U-tube in which the cross-sectional area of the limb on the left is one quarter, the limb on the right contains mercury (density 13.6 g/cm3). The level of mercury in the narrow limb is at a distance of 36 cm from the upper end of the tube. What will be the rise in the level of mercury in the right limb if the left limb is filled to the top with water?
Physics-Mechanical Properties of Fluids-79213.png
  • 1.2 cm
  • 2.35 cm
  • 0.56 cm
  • 0.8 cm
A homogeneous solid cylinder of length L (L < H/2).Cross-sectional area A/5 is immersed such that it floats with its axis vertical at the liquid-liquid interface with length L/4 in the denser liquid as shown in the fig. The lower density liquid is open to atmosphere having pressure P0. Then, density of solid is given by
Physics-Mechanical Properties of Fluids-79215.png

  • Physics-Mechanical Properties of Fluids-79216.png
  • 2)
    Physics-Mechanical Properties of Fluids-79217.png
  • d

  • Physics-Mechanical Properties of Fluids-79218.png
A wooden block, with a coin placed on its top, floats in water as shown in fig. the distance l and h are shown there. After some time the coin falls into the water. Then
Physics-Mechanical Properties of Fluids-79220.png
  • l decreases and h increases
  • l increases and h decreases
  • Both l and h increase
  • Both l and h decrease
A vessel contains oil (density = 0.8 gm/cm3) over mercury (density = 13.6 gm/cm3). A homogeneous sphere floats with half of its volume immersed in mercury and the other half in oil. The density of the material of the sphere in gm/cm is
  • 3.3
  • 6.4
  • 7.2
  • 12.8
A body floats in a liquid contained in a beaker. The whole system as shown falls freely under gravity. The upthrust on the body due to the liquid is
Physics-Mechanical Properties of Fluids-79222.png
  • Zero
  • Equal to the weight of the liquid displaced
  • Equal to the weight of the body in air
  • Equal to the weight of the immersed portion of the body
A liquid is kept in a cylindrical vessel which is being rotated about a vertical axis through the centre of the circular base. 1f the radius of the vessel is r and angular velocity of rotation is ω, then the difference in the heights of the liquid at the centre of the vessel and the edge is

  • Physics-Mechanical Properties of Fluids-79224.png
  • 2)
    Physics-Mechanical Properties of Fluids-79225.png

  • Physics-Mechanical Properties of Fluids-79226.png

  • Physics-Mechanical Properties of Fluids-79227.png
Water is filled in a cylindrical container to a height of 3m. The ratio of the cross-sectional area of the orifice and the beaker is 0.1. The square of the speed of the liquid coming out from the orifice is (g = 10 m/s2)
Physics-Mechanical Properties of Fluids-79229.png
  • 50 m2/s2
  • 50.5 m2/s2
  • 51 m2/s2
  • 52 m2/s2
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 arc the same. Then, R is equal to
  • 2πL
  • 2)
    Physics-Mechanical Properties of Fluids-79231.png
  • L

  • Physics-Mechanical Properties of Fluids-79232.png
A cylinder containing water upto a height of 25 cm has a hole of cross-section 1/4 cm2 in its bottom. It is counterpoised in a balance. What is the initial change in the balancing weight when water begins to flow out?
Physics-Mechanical Properties of Fluids-79234.png
  • Increase of 12.5 gm-wt
  • Increase of 6.25 gm-wt
  • Decrease of 12.5 gm-wt
  • Decrease of 6.25 grn-wt
There are two identical small holes of area of cross-section a on the opposite sides of a tank containing a liquid of density ρ. The difference in height between the holes is h. Tank is resting on a smooth horizontal surface. Horizontal force which will has to be applied on the tank to keep it in equilibrium is
Physics-Mechanical Properties of Fluids-79236.png
  • ghρa
  • 2)
    Physics-Mechanical Properties of Fluids-79237.png
  • 2ρagh

  • Physics-Mechanical Properties of Fluids-79238.png
Two communicating vessels contain mercury. The diameter of one vessel is n times larger than the diameter of the other. A column of water of height h is poured into the left vessel. The mercury level will rise in the right-hand vessel (s = Relative density of mercury and ρ = Density of water) by
Physics-Mechanical Properties of Fluids-79240.png

  • Physics-Mechanical Properties of Fluids-79241.png
  • 2)
    Physics-Mechanical Properties of Fluids-79242.png

  • Physics-Mechanical Properties of Fluids-79243.png

  • Physics-Mechanical Properties of Fluids-79244.png
A uniform rod of density ρ is placed in a wide tank containing a liquid of density ρo (ρo > ρ). The depth of liquid in the tank is half the length of the rod. The rod is in equilibrium, with its lower end resting on the bottom of the tank. In this position the rod makes an angle θ with the horizontal

  • Physics-Mechanical Properties of Fluids-79246.png
  • 2)
    Physics-Mechanical Properties of Fluids-79247.png

  • Physics-Mechanical Properties of Fluids-79248.png

  • Physics-Mechanical Properties of Fluids-79249.png
A block of ice floats on a liquid of density 1.2 in a beaker , then level of liquid when ice completely melt
  • Remains same
  • Rises
  • Lowers
  • (1), (or (3)
Water is filled up to a height h in a beaker of radius R as shown in the figure. The density of water is ρ, the surface tension of water is T and the atmospheric pressure is P0. Consider a vertical section ABCD of the water column through a diameter of the beaker. The force on water on one side of this section by water on the other side of this section has magnitude
Physics-Mechanical Properties of Fluids-79252.png

  • Physics-Mechanical Properties of Fluids-79253.png
  • 2)
    Physics-Mechanical Properties of Fluids-79254.png

  • Physics-Mechanical Properties of Fluids-79255.png

  • Physics-Mechanical Properties of Fluids-79256.png
A cylindrical vessel of height 500 mm has an orifice (small hole) at its bottom. The orifice is initially closed and water is filled in it up to height H. Now the top is completely sealed with a cap and the orifice at the bottom ¡s opened. Some water comes out from the orifice and the water level in the vessel becomes steady with height of water column being 200 mm. Find the fall in height (in mm) of water level due to opening of the orifice
[Take atmospheric pressure = 1.0 x 105 N/m2, density of water = 1000 kg/m3 and g = 10 m/s2. Neglect any effect of surface tension].
  • 5 mm
  • 6 mm
  • 2 mm
  • 1 mm
A uniform long tube is bent into a circle of radius R and it lies in a vertical plane. Two liquids of same volume but densities ρ and δ fill half the tube. The angle θ is
Physics-Mechanical Properties of Fluids-79259.png

  • Physics-Mechanical Properties of Fluids-79260.png
  • 2)
    Physics-Mechanical Properties of Fluids-79261.png

  • Physics-Mechanical Properties of Fluids-79262.png

  • Physics-Mechanical Properties of Fluids-79263.png
A small spherical solid ball is dropped from a great height in a viscous liquid. Its journey in the liquid is best described in the diagram given below by the
Physics-Mechanical Properties of Fluids-79265.png
  • Curve A
  • Curve B
  • Curve C
  • Curve D
An air bubble in a water tank rises from the bottom to the top. Which of the following statements are true?
  • Bubble rises upwards because pressure at the bottom is less than that at the top.
  • Bubble rises upwards because pressure at the bottom is greater than that at the top.
  • As the bubble rises, its size increases
  • As the bubble rises, its size decreases
  • Both (and (3)
Statement I The stream of water flowing at high speed from a garden hose pipe tends to spread like a fountain when held vertically up, but tends to narrow down when held vertically down.
Statement II In any steady flow of an in compressible fluid, the volume flow rate of the fluid remains constant.
  • Statement I is true, statement II is true ; statement II is a correct explanation for statement I
  • Statement I is true, statcment II is true ; statement II is not a correct explanation for statement I
  • Statement I is true, statement II is false
  • Statement I is false, statement II is true
Find the height of the water level h2 (in situation 2), for which the block remains in its original position without the application of any external force

  • Physics-Mechanical Properties of Fluids-79267.png
  • 2)
    Physics-Mechanical Properties of Fluids-79268.png

  • Physics-Mechanical Properties of Fluids-79269.png
  • h
Find the minimum value of height h1 (in situation 1), for which the block just starts to move up

  • Physics-Mechanical Properties of Fluids-79271.png
  • 2)
    Physics-Mechanical Properties of Fluids-79272.png

  • Physics-Mechanical Properties of Fluids-79273.png

  • Physics-Mechanical Properties of Fluids-79274.png
Two substances of densities ρ1 and ρ2 are mixed in equal volume and the relative density of mixture is 4. When they arc mixed in equal masses, the relative density of the mixture is 3. The values of ρ1 and ρ2 arc
  • ρ1 = 6 and ρ2 = 2
  • ρ1 = 3 and ρ2 = 5
  • ρ1 = 12 and ρ2 = 4
  • None of these
Two capillary tubes of same radius r but of lengths l1 and l2 are fitted in parallel to the bottom of a vessel. The pressure head is P. What should be the length of a single tube that can replace the two tubes so that the rate of flow is same as before

  • Physics-Mechanical Properties of Fluids-79277.png
  • 2)
    Physics-Mechanical Properties of Fluids-79278.png

  • Physics-Mechanical Properties of Fluids-79279.png

  • Physics-Mechanical Properties of Fluids-79280.png
Under a constant pressure head, the rate of flow of liquid through a capillary tube is V. If the length of the capillary is doubled and the diameter of the bore is halved, the rate of flow would become
  • V/4
  • 16 V
  • V/8
  • V/32
Small liquid drops assume spherical shape because
  • Atmospheric pressure exerts a force on a liquid drop
  • Volume of a spherical drop is minimum
  • Gravitational force acts upon the drop
  • Liquid tends to have the minimum surface area due to surface tension
The relative velocity of two consecutive layers is 8 cm/s. If the perpendicular distance between the layers is 0.1 cm, then the velocity gradient will be
  • 8 sec-1
  • 80 sec-1
  • 0.8 sec-1
  • 0.08 sec-1
A tank is filled upto a height h with a liquid and is placed on a platform of height h from the ground. To get maximum range xm a small hole is punched at a distance of y from the free surface of the liquid. Then
Physics-Mechanical Properties of Fluids-79284.png
  • xm = 2h
  • xm = 1.5 h
  • y = h
  • y = 0.75 h
  • Both (and (3)
A piston of cross-section area 100cm2 is used in a hydraulic press to exert a force of 107 dynes on the water. The cross-sectional area of the other piston which supports an object having a mass 2000 kg. is
  • 100 cm2
  • 109 cm2
  • 2 × 104 cm2
  • 2 × 1010 cm2
A cubical block of wood 10 cm on a side floats at the interface between oil and water with its lower surface horizontal and 4 cm below the interface. The density of oil is 0.6 g cm-3 . The mass of block is
Physics-Mechanical Properties of Fluids-79287.png
  • 706 g
  • 607 g
  • 760 g
  • 670 g
If W be the weight of a body of density ρ in vacuum, then its apparent weight in air of density σ is

  • Physics-Mechanical Properties of Fluids-79289.png
  • 2)
    Physics-Mechanical Properties of Fluids-79290.png

  • Physics-Mechanical Properties of Fluids-79291.png

  • Physics-Mechanical Properties of Fluids-79292.png
To get the maximum flight, a ball must be thrown as

  • Physics-Mechanical Properties of Fluids-79294.png
  • 2)
    Physics-Mechanical Properties of Fluids-79295.png

  • Physics-Mechanical Properties of Fluids-79296.png
  • Any of (, (and (
There is a horizontal film of soap solution. On it a thread is placed in the form of a loop. The film is pierced inside the loop and the thread becomes a circular loop of radius R. If the surface tension of the loop be T, then what will be the tension in the thread ?
  • πR2/T
  • πR2T
  • 2πRT
  • 2RT
In a surface tension experiment with a capillary tube, water rises upto 0.1 m. If the same experiment is repeated on an artificial satellite, which is revolving around the earth, water will rise in the capillary tube upto a height of
  • 0.1 m
  • 0.2 m
  • 0.98 m
  • Full length of the capillary tube
Two soap bubbles A and B are kept in a closed chamber where the air is maintained at pressure 8 N/m2. The radii of bubbles A and B arc 2 cm and 4 cm, respectively. Surface tension of the soap-water used to make bubbles is 0.04 N/m. Find the ratio nB/nA, where nA and nB are the number of moles of air in bubbles A and B, respectively. [Neglect the effect of gravity].
  • 2
  • 9
  • 8
  • 6
The correct curve between the height or depression h of liquid in a capillary tube and its radius is

  • Physics-Mechanical Properties of Fluids-79299.png
  • 2)
    Physics-Mechanical Properties of Fluids-79300.png

  • Physics-Mechanical Properties of Fluids-79301.png

  • Physics-Mechanical Properties of Fluids-79302.png
Which of the following statements are true in case when two water drops coalesce and make a bigger drop
  • Energy is released
  • Energy is absorbed
  • The surface area of the bigger drop is greater than the sum of the surface areas of both the drops
  • The surface area of the bigger drop is smaller than the sum of the surface areas of both the drops
  • Both (and (4)
Two solid spheres A and B of equal volumes but of different densities dA and dB are connected by a string. They are fully immersed in a fluid of density dF. They get arranged into an equilibrium state as shown in the figure with a tension in the string. The arrangement is possible only if
Physics-Mechanical Properties of Fluids-79304.png
  • dA < dF
  • dB > dF
  • dA > dF
  • dA + dB = 2dF
  • All (1), (and (4)
0:0:1


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