MEDIUM
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IMPORTANT
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The diagram shows venturimeter through which water is flowing. The speed of water at X is 2 cm sec-1. Find the speed of water in cm sec-1 at Y  taking g=1000 cm sec-2.

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Important Questions on Fluid Mechanics

EASY
JEE Main/Advance
IMPORTANT

In a movable container shown in figure a liquid of density ρ is filled up to a height h (1.8 m). The upper & lower tube cross sectional areas are A2 & A1 respectively A2>>A1. If the liquid leaves out the container through the tube of cross-sectional area A1 then find the velocity of liquid in m sec-1 coming out. Take g=10 m sec-2

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HARD
JEE Main/Advance
IMPORTANT

A large tank is filled with two liquids of specific gravities 2σ and σ. Two holes are made on the wall of the tank as shown. Find the ratio of the distance from O of the points on the ground where the jets from holes A & B strike. If the ratio is ab, find the value of (a+b).

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MEDIUM
JEE Main/Advance
IMPORTANT
Two vertical cylinder are connected by a small tube at the bottom. It contains a gas at constant temperature. Initially the piston are located at the same height. The diameters of the two cylinders are different. Outside the cylinder the space is vacuum. Gravitational acceleration is h0=20 cmm1=2 kg and m2=1 kg. The pistons are initially in equilibrium. If the masses of the piston are interchanged find the separation between the two pistons when they are again in equilibrium. Assume constant temperature.

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MEDIUM
JEE Main/Advance
IMPORTANT
A barometer is faulty. When the true barometer reading are 73 cm and 75 cm of Hg, the faulty barometer reads 69 cm and 70 cm respectively (i) What is the total length of the barometer tube? (ii) What is the true reading when the faulty barometer reads 69.5 cm? (iii) What is the faulty barometer reading when the true barometer reads 74 cm?
HARD
JEE Main/Advance
IMPORTANT

Length of horizontal arm of a uniform cross-section U-tube is =21 cm and ends of both of the vertical arms are open to surrounding of pressure 10500 N m-2. A liquid of density ρ=103 kg m-3 is poured into the tube such that liquid just fills the horizontal part of the tube. Now one of the open ends is sealed, and the tube is then rotated about a vertical axis passing through the other vertical arm with angular velocity ω0=10 rad s-1. If length of each vertical arm be a=6 cm. Calculate the length of air column in the sealed arm : g=10 m s-2

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HARD
JEE Main/Advance
IMPORTANT

A ball of density d is dropped onto a horizontal solid surface. It bounces elastically from the surface and returns to its original position in a time t1. Next, the ball is released and it falls through the same height before striking the surface of a liquid of density dL.

(a) If d < dL, obtain an expression (in terms of d , t1 and dL) for the time t2 the ball takes to come back to the position from which it was released.

(b) Is the motion of the ball simple harmonic?

(c) If d = dL, how does the speed of the ball depend on its depth inside the liquid ?
     Neglect all frictional and other dissipative forces. Assume the depth of the liquid to be large.

HARD
JEE Main/Advance
IMPORTANT

A container of large uniform cross-sectional area A resting on a horizontal surface, holds two immiscible, non-viscous and incompressible liquids of densities d and 2d, each of height H2 as shown in figure. The lower density liquid is open to the atmosphere having, pressure P0'

(i) A homogeneous solid cylinder of length LL<H2, crosssectional area A5 is immersed such that if floats with its axis vertical at the liquid-liquid interface with length L4 in the denser liquid. Determine:
(a) the density D of the solid,

(b) the total pressure at the bottom of the container.

(ii) The cylinder is removed and the original arrangement is restored. A tiny hole of area s (s<<A) is, punched on the vertical side of the container at a height hh<H2. Determine:
(a) the initial speed of efflux of the liquid at the hole

(b) the horizontal distance x travelled by the liquid initially, and

(c) the height hm at which the hole should be punched so that the liquid travels the maximum distance) xm initially. Also calculate xm. (Neglect the air resistance in these calculations)

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MEDIUM
JEE Main/Advance
IMPORTANT
A solid block of volume V=10-3 m3 and density d=800 kg m-3 is tied to one end of a string, the other end of which is tied to the bottom of the vessel. The vessel contains two immiscible liquids of densities ρ1=1000 kg m-3 and ρ2=1500 kg m-3. The solid block is immersed with 25th of its volume in the liquid of higher density and 35th in the liquid of lower density. The vessel is placed in an elevator which is moving up with an acceleration of a=g2. Find the tension in the string (in N).
[g=10 m s-2]