NEB Class 12 Science Fluids Mechanics Question Paper 2082 (Set B)

Group 'A' (Multiple choice questions)

Rewrite the correct option of each question in your answer sheet.

9 questions·1 marks each

1mcq1 marks

Bernoulli's equation relates:

A
Various force with change in momentum
B
Torque with change in angular momentum
C
Various forces involved in a fluid.
D
Various energy forms

bernoulli-equation

2mcq1 marks

For a given value of specific force, there are two possible depths which are known as:

A
sequent depths
B
Alternate depths
C
Critical depths
D
unsteady uniform

open-channelspecific-force

3mcq1 marks

The flow of liquid through a tapering pipe at constant rate is

A
steady uniform
B
Steady non-uniform
C
Unsteady non-uniform
D
Unsteady uniform

flow-classification

4mcq1 marks

The energy heads are expressed in term of energy per unit.

A
mass
B
weight
C
volume
D
density

energy-head

5mcq1 marks

Poise is a unit of :

A
Density
B
velocity gradient
C
dynamic viscosity
D
kinematic viscosity

viscosityunits

6mcq1 marks

The contraction loss coefficient K in term of coefficient of contraction in a pipe with a sudden contraction is:

A
$\left(\frac{1}{C_c} - 1\right)$
B
$\left(\frac{1}{C_c^{2}} - 1\right)$
C
$\left(\frac{1}{C_c^{2}} - 1\right)^{2}$
D
$\left(\frac{1}{C_c} - 1\right)^{2}$

minor-lossescontraction

7mcq1 marks

Continuity equation is valid for

A
incompressible fluid with unsteady flow.
B
incompressible fluid with steady flow.
C
Compressible fluid with unsteady flow.
D
Compressible fluid with steady flow.

continuity-equation

8mcq1 marks

The relation between Manning's roughness coefficient 'n' and Chezy's constant C is given by:

A
$C = \frac{1}{n} R^{1/6}$
B
$C = \frac{1}{n} R^{2/3}$
C
$C = nR^{1/6}$
D
$C = nR^{2/3}$

manningchezy

9mcq1 marks

The error in measurement of discharge is ... times the error in measurement of height of fluid over rectangular notch.

A
$1$
B
$1.25$
C
$1.15$
D
$1.5$

weirerror-analysis

Group 'B' (Short answer questions)

Attempt all the questions.

5 questions·5 marks each

10short5 marks

Define surface tension, viscosity compressibility, Newtonian fluid and Real fluid.

fluid-properties

11numeric5 marks

A $25\,\text{cm}$ diameter pipe carries oil of sp. gr 0.9 at a velocity of $3\,\text{m/s}$ . At another section the diameter is $20\,\text{cm}$ . Find the velocity at this section and also mass rate of flow of oil.

Numeric answer

continuitymass-flow-rate

12short5 marks

Derive Darcy- Weisbach equation for major head loss.

darcy-weisbachhead-loss

13numeric5 marks

Water flows at a uniform depth of $1.5\,\text{m}$ in a trapezoidal channel having a bottom width $5\,\text{m}$ and side slope 2H:1V. It has to carry a discharge of $60\,\text{m}^3/\text{s}$ . Compute the bottom slope required to be provided. Assume the bed material is gravel.

Numeric answer

open-channeltrapezoidal-channel

14numeric5 marks

A horizontal venturimeter with inlet and throat diameter $30\,\text{cm}$ and $15\,\text{cm}$ respectively is used to measure the flow of water. The reading of differential manometer connected to the inlet and throat is $20\,\text{cm}$ of mercury. Determine the rate of flow take $C_d = 0.98$ .

Numeric answer

venturimeterdischarge

Group 'C' (Long answer questions)

Attempt all the questions.

2 questions·8 marks each

15numeric8 marks

a) If 1 liter container is immersed halfway in water, what is the volume of water displaced? What is buoyant force in the container?

b) A hinged gate in a dam is inclined at $30^\circ$ from horizontal. The gate is $3.2\,\text{m}$ long $2.0\,\text{m}$ wide and hinged at A, at a depth of $1.7\,\text{m}$ . Calculate the magnitude of force to hold the gate closed.

Inclined hinged dam gate: water at depth 1.7 m, gate 3.2 m long at 30° hinged at A, force F_gate shown

Numeric answer

buoyancyhydrostatic-forceinclined-gate

16short8 marks

Mention general applications of Bernoulli's principle. Show, how discharge is measured through a pipe and using this principle.

bernoulliventurimeterdischarge-measurement