JEE Questions for Physics Mechanical Properties Of Fluids Quiz 14 - MCQExams.com

When liquid medicine of density p is to be put in the eye, it is done with the help of a dropper. As the bulb on the top of the dropper is pressed, a drop forms at the opening of the dropper. We wish to estimate the size of the drop. We first assume that the drop formed at the opening is spherical because that requires a minimum increase in its surface energy. To determine the size, we calculate the net vertical force due to the surface tension T when the radius of the drop is R. When this force becomes smaller than the weight of the drop, the drop gets detached from the dropper. If the radius of the opening of the dropper is r, the vertical force due to the surface tension on the drop of radius R (assuming r < < R) is
  • 2πrT
  • 2πRT

  • Physics-Mechanical Properties of Fluids-79306.png

  • Physics-Mechanical Properties of Fluids-79307.png
When liquid medicine of density p is to be put in the eye, it is done with the help of a dropper. As the bulb on the top of the dropper is pressed, a drop forms at the opening of the dropper. We wish to estimate the size of the drop. We first assume that the drop formed at the opening is spherical because that requires a minimum increase in its surface energy. To determine the size, we calculate the net vertical force due to the surface tension T when the radius of the drop is R. When this force becomes smaller than the weight of the drop, the drop gets detached from the dropper.If r = 5 × 10–4 m, ρ = 103 kgm–3 , g = 10 ms–2, T = 0.11 Nm–1, the radius of the drop when it detaches from the dropper is approximately
  • 1.4 × 10–3
  • 3.3 × 10–3
  • 2.0 × 10–3
  • 4.1 × 10–3
When liquid medicine of density p is to be put in the eye, it is done with the help of a dropper. As the bulb on the top of the dropper is pressed, a drop forms at the opening of the dropper. We wish to estimate the size of the drop. We first assume that the drop formed at the opening is spherical because that requires a minimum increase in its surface energy. To determine the size, we calculate the net vertical force due to the surface tension T when the radius of the drop is R. When this force becomes smaller than the weight of the drop, the drop gets detached from the dropper.After the drop detaches, its surface energy is
  • 1.4 × 10–6 J
  • 2.7 × 10–6 J
  • 5.4 × 10–6 J
  • 8.1 × 10–6 J
Assertion It is easier to spray water in which some soap is dissolved.
Reason Soap is easier to spread.
  • 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 hut Reason is false
  • If the Assertion and Reason both arc false
  • If Assertion is false but Reason is true
Assertion It is better to wash the clothes in cold soap
Reason The surface tension of cold solution is more than the surface tension of hot solution
  • 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 hut Reason is false
  • If the Assertion and Reason both arc false
  • If Assertion is false but Reason is true
Assertion When height of a tube is less than liquid rise in the capillary tube, the liquid does not overflow.
Reason Product of radius of meniscus and height of liquid in capillary tube always remains 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 hut Reason is false
  • If the Assertion and Reason both arc false
  • If Assertion is false but Reason is true
At which of the following temperatures, the value of surface tension of water is minimum?
  • 4°C
  • 25°C
  • 50°C
  • 75°C
Two pieces of glass plate one upon the other with a little water in between them cannot be separated easily because of
  • Inertia
  • Pressure
  • Surface tension
  • Viscosity
Surface tension is an atomic/molecular property of
  • Atoms in the interior
  • Atoms at surface
  • Atoms which are exterior
  • Atoms at surface bounded entirely by different atoms
Assertion A needle placed carefully on the surface of water may float, whereas a ball of the same material will always sink.
Reason The buoyancy of an object depends both on the material and shape 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 hut Reason is false
  • If the Assertion and Reason both arc false
  • If Assertion is false but Reason is true
Assertion A large force is required to draw apart normally two glass plates enclosing a thin water film.
Reason Water works as glue and sticks two glass plates.
  • 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 hut Reason is false
  • If the Assertion and Reason both arc false
  • If Assertion is false but Reason is true
Assertion The impurities always decreases the surface tension of a liquid
Reason The change in surface tension of the liquid depends upon the degree of contamination of the impurity.
  • 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 hut Reason is false
  • If the Assertion and Reason both arc false
  • If Assertion is false but Reason is true
Assertion The angle of contact of a liquid decrease with increase in temperature
Reason With increase in temperature , the surface tension of liquid increase.
  • 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 hut Reason is false
  • If the Assertion and Reason both arc false
  • If Assertion is false but Reason is true
Assertion The concept of surface tension is held only for liquids
Reason Surface tension does not hold for gases.
  • 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 hut Reason is false
  • If the Assertion and Reason both arc false
  • If Assertion is false but Reason is true
Assertion The shape of a liquid drop is spherical.
Reason The pressure inside the drop is greater than that of outside
  • 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 hut Reason is false
  • If the Assertion and Reason both arc false
  • If Assertion is false but Reason is true
Assertion The water rises higher in a capillary tube of small diameter than in the capillary tube of large diameter.
Reason Height through which liquid rises in a capillary tube is inversely proportional to the diameter of the capillary tube.
  • 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 hut Reason is false
  • If the Assertion and Reason both arc false
  • If Assertion is false but Reason is true
Assertion Tiny drops of liquid resist deforming forces better than bigger drops
Reason Excess pressure inside a drop is directly proportional to surface tension.
  • 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 hut Reason is false
  • If the Assertion and Reason both arc false
  • If Assertion is false but Reason is true
Water rises to a height of 16.3 cm in a capillary of height 18cm above the water level. 1f the tube is cut at a height of 12 cm
  • Water will come as a fountain from the capillary tube
  • Water will stay at a height of 12 cm in the capillary tube
  • The height of the water in the capillary will be 10.3 cm
  • Water will flow down the sides of the capillary tube
The diameter of rain-drop is 0.02 cm. If surface tension of water be 72 × 10–3 newton per metre, then the pressure difference of external and internal surfaces of the drop will be
  • 1.44 × 104 dyne – cm–2
  • 1.44 × 104 newton – m–2
  • 1.44 × 103 dyne – cm–2
  • 1.44 × 105 newton – m–2
When a capillary tube is dipped in water it rises up to 8 cm in the tube. What happens when the tube is pushed down such that its end is only 5 cm above the outside water level?
  • The radius of the meniscus increases and therefore water does not overflow
  • The radius of the meniscus decreases and therefore water does not overflow
  • The water forms a droplet on top of the tube but does not overflow
  • The water start overflowing
A bubble of 8 mm diameter is formed in the air. The surface tension of soap solution is 30 dynes/cm. The excess pressure inside the bubble is
  • 150 dynes/cm2
  • 300 dynes/cm2
  • 3 × 10-3 dynes/cm2
  • 12 dynes/cm2
A false statement is
  • Angle of contact θ < 90o, if cohesive force < adhesive force
  • Angle of contact θ > 90°, if cohesive force > adhesive force
  • Angle of contact θ = 90°, if cohesive force adhesive force
  • If the radius of capillary is reduced to half, the rise of liquid column becomes four times
Water rises to a height of 10 cm in capillary tube and mercury falls to a depth of 3.112 cm in the same capillary tube. If the density of mercury is 13.6 and the angle of contact for mercury is 135°, the ratio of surface tension of water and mercury is
  • 1 : 0.15
  • 1 : 3
  • 1 : 6
  • 1.5 : 1
The angle of contact between glass and water is 0o and it rises in a capillary upto 6 cm when its surface tension is 70 dynes/cm. Another liquid of surface tension 140 dynes/cm, angle of contact 60o and relative density 2 will rise in the same capillary by
  • 12 cm
  • 24 cm
  • 3 cm
  • 6 cm
A drop of water breaks into two droplets of equal size. In this process, which of the following statement is correct?
  • The sum of temperature of the two droplets together is equal to the original temperature of the drop
  • The sum of masses of the two droplets is equal to the original mass of the drop
  • The sum of the radii of two droplets is equal to the radius of the original drop
  • The sum of the surface areas of the two droplets is equal to the surface area of the original drop
A soap bubble of radius R is blown. After heating the solution a second bubble of radius 2R is blown. The work required to blow the second bubble in comparison to that required for the first bubble is
  • Double
  • Slightly less than double
  • Slightly less than four times
  • Slightly more than four times
Soap helps in cleaning clothes, because
  • Chemicals of soap change
  • It increases the surface tension of the solution
  • It absorbs the dirt
  • It lowers the surface tension of the solution
A wooden stick 2 m long is floating on the surface of water. The surface tension of water 0.07 N/m. By putting soap solution on one side of the sticks the surface tension is reduced to 0.06 N/m. The net force on the stick will be
  • 0.07 N
  • 0.06 N
  • 0.01 N
  • 0.02 N
The property utilized in the manufacture of lead shots is
  • Specific weight of liquid lead
  • Specific gravity of liquid lead
  • Compressibility of liquid lead
  • Surface tension of liquid lead
A square frame of side L is dipped in a liquid. On taking out, a membrane is formed. If the surface tension of the liquid is T, the force acting on the frame will be
  • 2 TL
  • 4 TL
  • 8 TL
  • 10 TL
Water does not wet an oily glass because
  • Cohesive force of oil > adhesive force between oil and glass
  • Cohesive force of oil > cohesive force of water
  • Oil repels water
  • Cohesive force for water > adhesive force between water and oil molecules
A water drop takes the shape of a sphere in a oil while the oil drop spreads in water, because
(A.E = adhesive force C.F. = cohesive force)
  • C.F. for water > A.F. for water and oil
  • C.F. for oil > A.F. for water and oil
  • C.F. for oil < A.F. for water and oil
  • None of the above
In the glass capillary tube, the shape of the surface of the liquid depends upon
  • Only on the cohesive force of liquid molecules
  • Only on the adhesive force between the molecules of glass and liquid
  • Only on relative cohesive and adhesive force between the atoms
  • Neither on cohesive nor on adhesive force
The force required to separate two glass plates of area 10–2 m2 with a film of water 0.05 mm thick between them, is (Surface tension of water is 70 × 10–3 N/m)
  • 28 N
  • 14 N
  • 50 N
  • 38 N
The surface tension of a liquid
  • Increases with area
  • Decreases with area
  • Increases with temperature
  • Decreases with temperature
It is easy to wash clothes in hot water because its
  • Surface tension is more
  • Surface tension is less
  • Consumes less soap
  • None of the above
Adding detergents to water helps in removing dirty greasy stains. This is because
1. It increases the oil-water surface tension
2. It decreases the oil-water surface tension
3. It increases the viscosity of the solution
4. Dirty is held suspended surrounded by detergent molecules
  • 2 and 4
  • 1 only
  • 3 and 4
  • 4 only
Two droplets merge with each other and forms a large droplet. In this process
  • Energy is liberated
  • Energy is absorbed
  • Neither liberated nor absorbed
  • Some mass is converted into energy
Radius of a soap bubble is ‘r\', surface tension of soap solution is T. Then without increasing the temperature, how much energy will be needed to double is radius ?
  • 4πr2 T
  • 2πr2 T
  • 12πr2 T
  • 24πr2T
A spherical liquid drop of radius R is divided into eight equal droplets. If surface tension is T, then the work done in this process will be
  • 2 πR2 T
  • 3 πP2 T
  • 4 πR2 T
  • 2 πRT2
A soap bubble of radius r is blown up to form a bubble of radius 2r under isothermal condition. If T is the surface tension of soap solution, the energy spent in the blowing, is
  • 3 πTr2
  • 6 πTr2
  • 12 πTr2
  • 24 πTr2
The surface tension of a liquid is 5 N/m . If a thin film of the area 0.02 m2 is formed on a loop, then its surface energy will be
  • 5 × 102 J
  • 2.5 × 10–2 J
  • 2 × 10–1 J
  • 5 × 10–1 J
The work done in blowing a soap bubble of radius r of the solution of surface tension T will be
  • 8πr2T
  • 2πr2T
  • 4πr2T

  • Physics-Mechanical Properties of Fluids-79328.png
Two small drops of mercury, each of radius R, coalesce to form a single large drop. The ratio of the total surface energies and before and after the change is
  • 1 : 21/3
  • 21/3 :1
  • 2 : 1
  • 1 : 2
A drop of mercury of radius 2 mm is split into 8 identical droplets. Find the increase in surface energy. (Surface tension of mercury is 0.465 J/m2)
  • 23.4 µ J
  • 18.5 µ J
  • 26.8 µ J
  • 16.8 µ J
The surface tension of a liquid at its boiling point
  • Becomes zero
  • Becomes infinity
  • Is equal to the value at room temperature
  • Is half to the value at the room temperature
What is ratio of surface energy of 1 small drop and 1 large drop, if 1000 small drops combined to form 1 large drop
  • 100 : 1
  • 1000 : 1
  • 10 : 1
  • 1 : 100
One thousand small water drops of equal radii combine to form a big drop. The ratio of final surface energy to the total initial surface energy is
  • 1000 : 1
  • 1 : 1000
  • 10 : 1
  • 1 : 10
The work done in increasing the size of a soap film from 10 cm × 6 cm to 10 cm × 11 cm is 3 × 10–4 joule. The surface tension of the film is
  • 1.5 × 10–2 N/m
  • 3.0 × 10–2 N/m
  • 6.0 × 10–2 N/m
  • 11.0 × 10–2 N/m
If σ be the surface tension, the work done in breaking a big drop of radius R in n drops of equal radius is
  • Rn2/3 σ
  • (n2/3 – 1)R σ
  • (n1/3 – 1)R σ
  • 4πR2(n1/3 –σ
0:0:1


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Physics Quiz Questions and Answers