Fluids Test

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Fluids Test - 9

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Weekly Quiz Competition

Question 1
1 / -0

A large number of liquid drops each of radius r coalesce to form a single drop of radius R. The energy released in the process is converted into the kinetic energy of the big drop so formed. The speed of the big drop is(given surface tension of liquid is T, density of liquid is ρ)

A

B

C

D

Solution
Question 2
1 / -0

The intensive property among the following is

A
energy

B
volume

C
entropy

D
temperature

Solution

Intensive properties are those which do not depend on the quantity of matter present. Properties like temperature, surface tension etc are intensive. Choice 4 is correct.

On the other hand properties which depend upon the quantity of matter present are called extensive properties like volume, mass, energy, entropy etc.
Question 3
1 / -0

If the work done in blowing a soap bubbie of volume V is W, then the work done in blowing a soap bubble of volume 2V will be

A
W

B
2W

C
√2W

D
W (4)^1/3

Solution

W' = W × 4^1/3
Question 4
1 / -0

A closed rectangular tank is completely filled with water and is accelerated horizontally with an acceleration towards right. Pressure is

(i) maximum at, and (ii) minimum at

A
(i) B (ii) D

B
(i) C (ii) D

C
(i) B (ii) C

D
(i) B (ii) A

Solution

dp/dx = −ρa (along horizontal towards right) i.e. in the direction of acceleration along horizontal pressure will decrease of p_AB> p_CD

dp/dy = −ρg (along vertically upwards direction pressure will decease.)
Question 5
1 / -0

A tank is filled to a height H. The range of water coming out of a hole which is a depth H/4 from the surface of water level is

A
2H/√3

B
√3H/2

C
√3H

D
3H/4

Solution
Question 6
1 / -0

The material of a wire has density of 1.4 gm/cm³. If it is not wetted by a liquid of surface tension 44 dyne/cm then the maximum radius of the wire which can float on the surface of liquid is

A
1/7 cm

B
5/7 cm

C
5/14 cm

D
2/7 cm

Solution

Let L be the length of wire and r be its radius. then for it weight of wire to be just supported (not wetted completely by liquid) is equal to the force due to surface.tension.

Since πr²Lρg = 2T × L
Question 7
1 / -0

Sudden fail of atmospheric pressure by a large amount indicates

A
storm

B
rain

C
fair weather.

D
cold wave.

Solution

Sudden fall of atmospheric pressure shows that pressure has lowered at site and Indicates storm, as the air from other places will soon rush to equalize pressure.
Question 8
1 / -0

Two equal drops of water are falling through air with a steady velocity v. If the drops coalesce, the new velocity will be

A
2v

B
√2v

C
2^2/3v

D
v/√2

Solution

Let r be the radius of smaller drop and R the radius of bigger drop. By equating the volumes we have,

Now terminal velocity ∝∝ (radius)²

∴ v'= 2^2/3v
Question 9
1 / -0

A body of density d₁ is counter poised by Mg of weights of density d₂ in air of density d. Then the true mass of the body is

A
M

B

C

D

Solution

Let M₀ g be weight of body in vaccum then, weight of body in air = weight of standard weights in air

Where losses of weights due to displaced air by body and standard weights are respectively
Question 10
1 / -0

A tank filled with water has two taps to exhaust and pour. A hollow spherical ball is half submerged in water. Through one tap, water is taken out and through another tap, a liquid of density double the density of water is poured in tank such that volume of liquid in tank remains constant. Sphere will

A
go down

B
go up

C
maintain same height

D
sink to bottom

Solution

If density of liquid ρl is increased, immersed volume V_i, will decrease or the ball will go up.