Previous Year Papers

Download Solved Question Papers Free for Offline Practice and view Solutions Online.

Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.

Mechanical Properties of Fluids

Multiple Choice Questions

141.
A given shaped glass tube having uniform cross section is filled with water and is mounted on a rotatable shaft as shown in figure. If the tube is rotated with a constant angular velocity ω when

water levels in both sections A and B go up

water level in section A goes up and that in B comes down

water level in section A comes down and that in B it goes up

water levels remain same in both sections

water levels in both sections A and B go up

Due to rotation about the OO', a force is acting on the liquid column AB outwards, pushing up the liquid column AB outwards, pushing up the liquid column on the right. This centrifugal force acting on the small element 'dx' of area cross-section 'dx', distant x from the axis is

dm ω²x = A dx ρω²x

The total force due to the column of length L ( = AB ) is

$\int_{0}^{L}$ Aρω² · x dx = A ρω² $\frac{L^{2}}{2}$

Pressure at B = atmospheric pressure + h₁ρg + $\frac{{Aρω}^{2}}{A} \frac{L^{2}}{2}$

Pressure at B due to liquid colomn on the right hand side

= atmospheric pressure + h₂ρg

Net pressure due to the left-hand side = pressure at B due to liquid column

atm. pressure + h₁ρg + ρω² $\frac{L^{2}}{2}$ = atm. pressure + h₂ρg

∴ h₂ $-$ h₁ = H₀ = $\frac{ω^{2} L^{2}}{2 g}$

Here one has

H₂ = $\frac{ω^{2} L_{2}^{2}}{2 g}$

H₁ = $\frac{ω^{2} L_{1}^{2}}{2 g}$

As ω is the same, and L₂ > L₁, H₂ > H₁

But both will go up.

142.

Assertion: Specific gravity of a fluid is a dimensionless quantity

Reason: : It is the ratio of density of fluid to the density of water.

If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false

143.

Assertion: For Reynold number R_e > 2000, the flow of fluid is turbulent.

Reason: Inertial forces are dominant compared to the
viscous forces at such high Reynold numbers.

If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false

144.

A sphere of mass Mand radius R is falling in a viscous fluid. The terminal velocity attained by the falling object will be proportional to

R²
R
1/R
1/R²

145.

The old age arteries carrying blood in the human body become barrow resulting in an increase in blood pressure. This follows from

Pascal's law
Stoke's law
Bernoulli's principle
Archimedes principle

146.

Assertion: Smaller drops of liquid resist deforming forces better than the larger drops.

Reason: Excess pressure inside a drop is directly proportional to its surface area

If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If assertion is true but reason is false

147.

Bernoulli's equation is a consequence of conservation of

energy
linear momentum
angular momentum
mass

148.

Two small drops of mercury, each of radius R, coalesce to form a single large drop. The ratio of the total surface energies before and after change is

1 : 2^1/3
2^1/3 : 1
2 : 1
1 : 2

149.

Scent sprayer is based on

Charle's law
Archimedes principle
Boyle's law
Bernoulli's theorem

150.

The property utilized in the manufacture of lead shots is

specific weight of liquid lead
compressibility of liquid lead
specific gravity of liquid lead
surface tension of liquid lead