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What are fluids? Mention some of their basic properties.

Important Questions on Mechanical Properties of Fluids

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An open-ended U-tube of uniform cross-sectional area contains water (density 103 kg m-3 ). Initially the water level stands at 0.29 m from the bottom in each arm. Kerosene oil (a water-immiscible liquid) of density 800 kg m-3 is added to the left arm until its length is 0.1 m, as shown in the schematic figure below. The ratio h1h2 of the heights of the liquid in the two arms is

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There is a circular tube in a vertical plane. Two liquids which do not mix and of densities d1 and d2 are filled in the tube. Each liquid subtends 90o angle at centre. Radius joining their interface makes an angle α with vertical. Ratio d1d2  is:
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HARD

A cylindrical vessel containing a liquid is rotated about its axis so that the liquid rises at its sides as shown in the figure. The radius of vessel is 5 cm and the angular speed of rotation is ω rad s-1. The difference in the height, h in cm of liquid at the Centre of vessel and at the sides of the vessel will be :

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EASY
The pressure at the bottom of a liquid tank is not proportional to the
MEDIUM
Two thin circular discs A and B of radii 2 cm and 4 cm are in a liquid at the same depth. TA is the thrust on A and TB thrust on B. Then TA:TB=
EASY

Water stands upto height 'h' behind the dam as shown in the figure. The front view of the dam gate is also shown in the adjoining figure. Density of water is 'ρ' and acceleration due to gravity is 'g'. If atmospheric pressure force is also considered, the point of application of total force acting on the dam due to water above 'o' is_____

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Two liquids of densities ρ1 and ρ2ρ2=2ρ1 are filled up behind a square wall of side 10 m as shown in figure. Each liquid has a height of 5 m. The ratio of the forces due to these liquids exerted on upper part MN to that at the lower part NO is (Assume that the liquids are not mixing):

HARD
A thin uniform tube is bent into a circle of radius r in the vertical plane. Equal volumes of two immiscible liquids, Whose densities are ρ1 and ρ2 (ρ1>ρ2 ), fill half the circle. The angle θ between the radius vector passing through the common interface and the vertical is:
EASY
In Guericke's experiment to show the effect of atmospheric pressure, two copper hemispheres were tightly fitted to each other to form a hollow sphere and the air from the sphere was pumped out to create vacuum inside. If the radius of each hemisphere is R and the atmospheric pressure is P, then the minimum force required (when the two hemispheres are pulled apart by the same force) to separate the hemispheres is
MEDIUM
A long cylindrical vessel is half filled with a liquid. When the vessel is rotated about its own vertical axis, the liquid rises up near the wall. If the radius of vessel is 5 cm and its rotational speed is 2 rotations per second, then the difference in the heights between the center and the sides, in cm, will be:
EASY
The pressure acting on a submarine is 3×105 Pa at a certain depth. If the depth is doubled, the percentage increase in the pressure acting on the submarine would be: (Assume that atmospheric pressure is 1×105 Pa density of water is 103 kg m-3, g=10 ms-2)
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A cylindrical vessel of base radius R and height H has a narrow neck of height h and radius r at one end (see figure). The vessel is filled with water (density ρw ) and its neck is filled with immiscible oil (density ρ0). Then the pressure at;
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EASY

The liquid shown in the figure in the two arms is mercury (specific gravity 13.6) and water. If the difference of heights of the mercury column is 2 cm, the height h of the water column is

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HARD
Consider a vessel filled with a liquid upto height H. The bottom of the vessel lies in the X-Y plane passing through the origin. The density of the liquid varies with Z-axis as ρz=ρ02-zH2. If P1 and P2 are the pressures at the bottom surface and top surface of the liquid, the magnitude of P1-P2 is :
HARD

A cylindrical tube, with its base as shown in the figure., is filled with water. It is moving down with a constant acceleration a along a fixed inclined plane with angle θ=45°P1 and P2 are pressures at point 1 and 2, respectively, located at the base of the tube. Let β=P1P2ρgd, where ρ is density of water, d is the inner diameter of the tube and g is the acceleration due to gravity. Which of the following statement(s) is (are) correct?

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MEDIUM
A U tube with both ends open to the atmosphere is partially filled with water. Oil, which is immiscible with water, is poured into one side until it stands at a distance of 10 mm above the water level on the other side. Meanwhile, the water rises by 65 mm from its original level (see diagram). The density of the oil is ____ρw=1000 kg m-3
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A barometer is constructed using a liquid (density =760 kg m-3). What would be the height of the liquid column, when a mercury barometer reads 76 cm?

(density of mercury =13600 kg m-3)

HARD
Two spheres P and Q of equal radii have densities ρ1 and ρ2 , respectively. The spheres are connected by a massless string and placed in liquids L1 and L2 of densities σ1 and σ2 and viscosities η1 and η2 , respectively. They float in equilibrium with the sphere P in L1 and sphere Q in L2 and the string being taut (see figure). If sphere P alone in L2 has terminal velocity VP and Q alone in L1 has terminal velocity VQ , then

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EASY
The velocity of water in river is 18 km h-1 near the surface. If the river is 5 m deep, then the shearing stress between the surface layer and the bottom layer is (coefficient of viscosity of water, η=10-3 Pa s)
MEDIUM
A piece of copper having a rectangular cross-section of 15.2 mm x 19.1 mm is pulled in tension with 44,500 N force, producing only elastic deformation. Calculate the resulting strain? Shear modulus of elasticity of copper is 42 x 109 N m-2.