Mechanical Properties of Fluids

Class 11th Physics – 10 Mechanical properties of fluids MCQs

If a small hole is made at a height of 1/√2 m from the bottom of a cylindrical water tank and at a depth of h = √2 m from the upper level of water in the tank, then the water emerging from the hole would strike the ground at a distance of ____.

Correct! Wrong!

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Velocity of the efflux v =√(2gh) Time taken to fall the height of (H - h ) meter is t = √ [2(H−h)]/g Horizontal distance from the tank is given by x = v× t

The density of the atmosphere at sea level is 2.50 kg/m3. If it does not change with altitude, then the atmosphere would extend for ____.

Correct! Wrong!

Here, density (d) = 2.50 kg/m3 acceleration due to gravity (g) = 9.8 m/s2 atmospheric pressure (P) 1.01 × 105 Pa
Then, P = hdg
1.01 × 105 = h × 2.50 × 9.8
1.01×105/2. 50×9. 8= h
h = 3.959 km

A square plate of area 3 sq. metres is separated from a large plate by a layer of oil 3 mm thick. If coefficient of viscosity of this oil is 0.01 Pa s, then the force required to keep the plate moving with a velocity of 6 cm/s is ____.

Correct! Wrong!

A square plate of area 3 sq. metres is separated from a large plate by a layer of oil 3 mm thick. If coefficient of viscosity of this oil is 0.01 Pa s, then the force required to keep the plate moving with a velocity of 6 cm/s is ____.

The liquid used in a digital sphygmomanometer is ____.

Correct! Wrong!

There is no liquid used in a digital sphygmomanometer.

Blood pressure is due to the force exerted by circulating blood on the walls of ____.

Correct! Wrong!

Blood pressure is due to the force exerted by circulating blood on the walls of blood vessels, namely arteries and veins.

Consider that a barometer tube is inclined at an angle of 60° with the horizontal direction. If the atmospheric pressure is 65 cm of Hg, the length of mercury column in the barometer tube will be ____.

Correct! Wrong!

Here, h = 65 cm sin600=√3/2 1=h/sin600 =(65)/(√3/2) =65×2/√3= 75 . 05 cm

The press plunger of a hydraulic pressure is 5 m2 in cross-section and is required to overcome a resistive load of 500 kg f . If the area of cross-section of the press plunger is 0.01 m2, then the force required on the pump plunger will be ____.

Correct! Wrong!

Let F be the force required on the pump plunger. By Pascal's law, Pressure on pump plunger = Pressure on press plunger F/0 .01 = 500/5 Therefore, F = 0.01 × 100 = 1 kg f

Surface tension may be defined as ____.

Correct! Wrong!

Surface tension = Work done per unit area in increasing the surface area of a liquid under isothermal conditions.

Which of the following is true regarding condition for a Venturimeter to measure the rate of flow of a liquid?

Correct! Wrong!

For measuring the rate of flow of a liquid by a Venturimeter, the liquid should be incompressible.

If the flow of water in a tube of diameter 3 cm is linear, then the average velocity of water is____. (Note: Assume viscosity of water is 0.001 Pa-s)

Correct! Wrong!

Here, D = 3 cm = 0.03 m, η = 0.001 Pa-s, ρ = 103 kg/m3
Thus, for a stream line flow, NR = 2000
∴v = NRη/ρD = 2000×0 . 001/103×0. 03 = 0.07 ms-1

An incompressible fluid flows steadily through a cylindrical pipe which has radius 2R at point A and radius R at point B farther along the flow direction. If the velocity at point A is v, then its velocity at point B will be____.

Correct! Wrong!

From equation of continuity, Π (2R)2 v = Πr2 v1
Therefore, v1 = 4 v

What is the principle on which Venturimeter is based?

Correct! Wrong!

A Venturimeter is developed based on Bernoulli’s principle.

Three exactly similar rain drops falling with terminal velocity 3 ms-1 coalesce to form a bigger drop. The new terminal velocity of the bigger drop will be____.

Correct! Wrong!

Volume of bigger drop = Volume of three small drops
4/3 π R3 = 3×4/3 π r3
⇒R3 = 3r3 or R/r = 31/3
Terminal velocity of the smaller drop v1= (2/9)(r2/η) (ρ- σ)g
Terminal velocity of the bigger drop v2= 2/9 R2 /η(ρ−σ)g
∴v2/v1 = R2/r2 = 31/3= 32/3
∴v2= 32/3×3 = 35/3 ms-1

The surface tension of a liquid at critical temperature is ____

Correct! Wrong!

The surface tension of a liquid at critical temperature is zero.

If liquid rises in a tube due to capillary action, the angle of contact would be ____.

Correct! Wrong!

If liquid rises in a capillary tube, then h is positive. Therefore, cos θ is +ve. If cos θ is +ve, θ < 90° or θ is acute.

If a non-wetting liquid is displaced in a capillary tube, the shape of the liquid when seen from below would be ____ .

Correct! Wrong!

Being a non-wetting liquid, it will not wet the sides of capillary tube and hence, will have a meniscus convex upwards. The angle of contact will be greater than 90°. So, when the upwards convex meniscus is seen from below, it will look as concave downwards.

Surface tension of a liquid is due to ____.

Correct! Wrong!

Surface tension of a liquid is due to force of attraction between like molecules of a liquid i.e., cohesive force between molecules.

If temperature increases, angle of contact ____.

Correct! Wrong!

When the temperature increases, the surface tension of the liquid decreases. As surface tension is indirectly proportional to angle of contact, angle of contact increases.

If the level of water in a tank is 5 m high and a hole of area 1 cm2 is made in the bottom of the tank, then the rate of leakage of water from the hole will be ____. (assume g = 10 ms-2)

Correct! Wrong!

Here, Velocity of efflux v = √2gh, Volume of liquid flowing out per second =v×A = √ (2gh)×A = √(2×10×5)× 10- 4=10- 3m3/s

In a hydraulic machine, the two pistons have area of cross-section in the ratio 1:10. The force needed on the narrow piston to overcome a force of 100 N on the wider piston is ____ .

Correct! Wrong!

A1 = 1 A2 = 10 F1 =? F2 = 100 N
By the principle of hydraulic machine,
F1/A1 = F2A2
F1/1 = 100/10
Therefore, F1 = 10 N

The intermolecular distance is the least in ___ and the highest in ___.

Correct! Wrong!

The intermolecular distance is the least in solids and the highest in gases.

Fluids are

Correct! Wrong!

The material that has the property to flow is referred to as a fluid. Hence, both liquids and gases combined together are called fluids.

In a streamline flow, the velocity of flow at a point in the liquid ____

Correct! Wrong!

In a streamline flow, the velocity of flow at a point in the liquid does not vary with time.

In Bernoulli's theorem, ____ is conserved.

Correct! Wrong!

According to Bernoulli's theorem, only law of conservation of energy is maintained.

Bernoulli's equation is important in the field of____

Correct! Wrong!

Bernoulli's theorem is an indispensable tool for the analysis of flow of liquids.

The SI unit of pressure is ____.

Correct! Wrong!

Pressure is force per unit area. Hence, the SI unit of pressure is the ratio of SI unit of force to SI unit of area, which is N/m2.

The concentration of streamlines around a ball in motion through air represents the ____.

Correct! Wrong!

The concentration of streamlines around a ball in motion through air represents the magnitude of velocity of air.

A square flat plate of side 25 cm moves over another similar plate with a thin layer of 0.4 cm of a liquid between them. If a force of 1 kg.wt moves one of the plates uniformly with a velocity of 1 ms-1, then the coefficient of viscosity will be ____. (Assume g = 9.8 × ms-2)

Correct! Wrong!

Here, A = 25 × 25 = 625 × 10-4 m2, F =1 kg.wt = 1 × 9.8 N; dv = 1 ms-1; dx = 0.4 cm = 0.4 × 10-2 m
So, η = F/A(dvdx) = F dx/A dv = 9 . 8×0. 4×10- 2/625×10- 4×1 = 0. 63 Pa s

The dynamic lift due to the additional spin motion of a ball along with its translational motion in air is also called the Magnus effect.

Correct! Wrong!

The dynamic lift due to the additional spin motion of a ball along with its translational motion in air is also called the Magnus effect.

The blood vessels that carry blood from the heart to other parts of the body are _____ and those that return blood to the heart are ____.

Correct! Wrong!

The blood vessels that carry blood from the heart to other parts of the body are arteries and those that return blood to the heart are veins.

Class 11th Physics - 10 Mechanical properties of fluids MCQs
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