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Earn 100

Define range of molecular attraction.

Important Questions on Mechanical Properties of Fluids

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A water drop of diameter 2 cm is broken into 64 equal droplets. The surface tension of water is 0.075 N m-1. In this process the gain in surface energy will be
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Two small drops of mercury each of radius R coalesce to form a single large drop. The ratio of total surface energy before and after the change is
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Water does not wet an oily glass because
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Surface tension of a soap bubble is 2.0×10-2 N m-1 . Work done to increase the radius of soap bubble from 3.5 cm to 7 cm will be : [Take π=227 ]
EASY
Two droplets coalesce in a single drop. In this process _______.
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If 1000 droplets of water of surface tension 0.07 N m-1. having same radius 1 mm each, combine to from a single drop. In the process the released surface energy is-

Take π=227

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A drop of radius R breaks into n equal drops. What is the ratio of total final surface energy to initial surface energy?
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If 'M' is the mass of water that rises in a capillary tube of radius 'r' , then mass of water which will rise in a capillary tube of radius '2r' is:
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A big water drop is formed by the combination of n small water drops of equal radii. The ratio of the surface energy of n drops to the surface energy of the big drop is
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A liquid does not wet the solid surface if angle of contact is:
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A mercury drop of radius 103 m is broken into 125 equal size droplets. Surface tension of mercury is 0.45 N m1 . The gain in surface energy is:
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Work done in increasing the size of a soap bubble from radius of (3 to 5) cm is nearly (surface tension of soap solution =0.03 N m-1)
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The amount of energy required to form a soap bubble of radius 2 cm from a soap solution is nearly: (surface tension of soap solution = 0.03 N m-1)
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A spherical drop of liquid splits into 1000 identical spherical drops. If ui is the surface energy of the original drop and uf is the total surface energy of the resulting drops, the (ignoring evaporation), ufui=10x. Then value of x is ______:
EASY
The radius R of the soap bubble is doubled under isothermal condition. If T be the surface tension of the soap bubble, the work done in doing so is given by
HARD

When water is filled carefully in a glass, one can fill it to a height h above the rim of the glass due to the surface tension of water. To calculate h just before water starts flowing, model the shape of the water above the rim as a disc of thickness h having semicircular edges, as shown schematically in the figure. When the pressure of water at the bottom of this disc exceeds what can be withstood due to the surface tension, the water surface breaks near the rim and water starts flowing from there. If the density of water, its surface tension and the acceleration due to gravity are 103 kg m-3,0.07 N m-1 and 10 m s-2 respectively, the value of h (in mm) is ________.

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EASY

When a long glass capillary tube of radius 0.015 cm is dipped in a liquid, the liquid rises to a height of 15 cm within it. If the contact angle between the liquid and glass is close to 0°, the surface tension of the liquid, is n Millinewton m-1. Write the value of 100n.

ρ(liquid) =900 kg m-3, g=10 m s-2

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Work done in increasing the size of a soap bubble from a radius of 3 cm to 5 cm is nearly (surface tension of soap solution =0.05Nm-1)
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Two small drops of mercury each of radius R coalesce to form a large single drop. The ratio of the total surface energies before and after the change is
HARD
A large number of liquid drops each of radius r coalesce to form a single drop of the radius R. The energy released in the process is converted into kinetic energy of the big drop so formed. The speed of the big drop is (given surface tension of the liquid T, density ρ)