Q1: The venturimeter works on [2023]
A: Huygen’s principle
B: Bernoulli’s principle
C: The principle of parallel axes
D: The principle of perpendicular axes
Ans: B
Solution: Venturimeter works on the Bernoulli’s principle.
Q2: A spherical ball is dropped in a long column of a highly viscous liquid. The curve in the graph shown, which represents the speed of the ball (v) as a function of time (t) is [2022]
A: B
B: C
C: D
D: A
Ans: A
Solution: Initial speed of ball is zero and it finally attains terminal speed
Q1: If a soap bubble expands, the pressure inside the bubble [2022]
A: Increases
B: Remains the same
C: Is equal to the atmospheric pressure
D: Decreases
Ans: D
Solution:
Excess pressure inside the bubble =
P = P_{0 }+ 4T/R
as ‘R’ increases ‘P’ decreases
Q1: The velocity of a small ball of mass M and density d, when dropped in a container filled with glycerine becomes constant after some time. If the density of glycerine is d/2, then the viscous force acting on the ball will be: [2021]
A: 3/2Mg
B: 2Mg
C: Mg/2
D: Mg
Ans: C
Solution:
Mass = M
Density of ball = d
Density of glycerine = d/2
Q1: 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 }) [2020]
A: 1.36 m
B: 13.6 m
C: 136 m
D: 0.76 m
Ans: B
Density of liquid, ρl = 760 kg /m^{3}
Density of mercury, ρm = 13600 kg /m^{3}
Height of liquid column in mercury barometer,
hm = 76 cm = 0.76 m
If height of liquid in liquid column be hl , then
Q2: A liquid does not wet the solid surface if angle of contact is [2020]
A: equal to 45°
B: equal to 60°
C: greater than 90°
D zero
Ans: C
A liquid does not wet the solid surface, if the angle of contact is obtuse i.e., θ > 90º.
Q1: A soap bubble, having radius of 1 mm, is blown from a detergent solution having a surface tension of 2.5 × 10^{2} N/m. The pressure inside the bubble equals at a point Z_{0} below the free surface of water in a container. Taking g = 10 m/s^{2}, density of water = 10^{3} kg/m^{3}, the value of Z_{0} is [2019]
A: 100 cm
B: 10 cm
C: 1 cm
D: 0.5 cm
Ans: C
Solution:
Excess pressure = 4T/R, Gauge pressure
Q2: A small hole with area area of crosssection 2 mm^{2} is present near the bottom of a fully filled open tank of height 2 m. Taking g = 10 m/s^{2}, the rate of flow of water through the open hole would be nearly [2019]
A: 12.6 × 10^{–6} m^{3}/s
B: 8.9 × 10^{–6} m^{3}/s
C: 2.23 × 10^{–6} m^{3}/s
D: 6.4 × 10^{–6} m^{3}/s
Ans: A
Solution:
Rate of liquid flow
Q1: A small sphere of radius 'r' falls from rest in a viscous liquid. As a result, heat is produced due to viscous force. The rate of production of heat when the sphere attains its terminal velocity, is proportional to: [2018]
A: r^{3}
B: r^{2}
C: r^{5}
D: r^{4}
Ans: C
Solution:
Q1: 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: [2017]
A: 425 kg m^{–3}
B: 800 kg m^{–3}
C: 928 kg m^{–3}
D: 650 kg m^{–3}
Ans: C
Solution:
Q1: Two nonmixing liquids of densities ρ and nρ (n > 1) are put in container. The height of each liquid is h. A solid cylinder of length L and density d is put in this container. The cylinder floats with its axis vertical and length pL (p < 1) in the denser liquid. The density d is equal to [2016]
A: {1 + (n  1)p}ρ
B: {1 + (n + 1)p}ρ
C: {2+(n + 1)p}ρ
D: {2 + (n  1)p}ρ
Ans: A
Solution:
wt of body = upthrust by the two liquids
If A = Area of section then
Q1: The approximate depth of an ocean is 2700 m. The compressibility of water is 45.4 x 10^{11} Pa^{1} and density of water is 103 kg/m^{3}. What fractional compression of water will be obtained at the bottom of the ocean? [2015]
A: 1.4 x 10^{2}
B: 0.8 x 10^{2}
C: 1.0 x 10^{2}
D: 1.2 x 10^{2}
Ans: D
Solution:
Q2: A wind with speed 40 m/s blows parallel to the roof of a house. The area of the roof is 250 m^{2}. Assuming that the pressure inside the house is atmospheric pressure, the force exerted by the wind on the roof and the direction of the force will be:
(Pair = 1.2 kg/m^{3}) [2015]
A: 2.4 x 10^{5} N, downwards
B: 4.8 x 10^{5} N, downwards
C: 4.8 x 10^{5} N, upwards
D: 2.4 x 10^{5} N, upwards
Ans: D
Solution:
Q1: A certain number of spherical drops of a liquid of radius ‘r’ coalesce to form a single drop of radius ‘R’ and volume ‘V’. If ‘T’ is the surface tension of the liquid, then: [2014]
A:
B: energy is neither released nor absorbed
C:
D:
Ans: A
Solution:
102 videos411 docs121 tests

1. What are the different types of mechanical properties of fluids? 
2. How does viscosity affect the flow of fluids? 
3. What is the significance of surface tension in fluid mechanics? 
4. How does compressibility affect the behavior of fluids under pressure? 
5. What is the bulk modulus of a fluid and how does it relate to its compressibility? 

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