Quiz: Civil Engineering

Exam: SSC-JE

Topic: MISCELLANEOUS

Each question carries 1 mark

Negative marking: 1/4 mark

Time: 10 Minutes

Q1. While designing a hydraulic structure, the piezometric head at bottom of the floor is computed as 10m. The datum is 3 m below floor bottom. The assured standing water depth above the floor is 2 m. The specific gravity of the floor material is 2.5 The floor thickness should be

(a) 2.00 m

(b) 3.33 m

(c) 4.40 m

(d) 6.00 m

Q2. The depth of flow in a alluvial channel is 1.5 m. If critical velocity ratio is 1.1 and Manning’s n is 0.018, the critical velocity of the channel as per Kennedy’s method is

(a) 0.713 m/s

(b) 0.784 m/s

(c) 0.879 m/s

(d) 1.108 m/s

Q3. In an iceberg 15% of the volume projects above the sea surface. It the specific weight of sea water is 0.5 kN/m³. the specific weight of iceberg in kN/m³ is

(a) 12.52

(b) 9.81

(c) 8.93

(d) 7.83

Q4. One of the following statements is true with regards to bodies that float or are submerged in liquieds:

(a) for a body wholly submerged in a liquid the stability is ensured if the center of buoyancy is below the center of gravity of the body.

(b) for a body floating in liquid the stability is ensured if the center of buoyance is below the center of gravity of the body.

(c) for a body floating in a liquid the stability is ensured if the center of buoyance is below the centre of gravity.

(d) for a body floating in a liquid the stability is ensured if the center of buoyance is below the centre of gravity and the metacenter is above bot the centres of gravity and buoyancy.

Q5. The velocity component in the X and y directions for an incompressible flow are given

u=(-5+6x)& V=(9+6y)

Respectively. The eq^n of streamline

(a) (-5+6x)-(9+6y)=const

(b) (-5+6x)/(9+6y)=const

(c) (9+6y)/(-5+6x)=const

(d) (-5s+6x) (9+6y)=cosnt

Q6. A ‘V’ notch is used for discharge measurement in a channel flow. If there is 1.5 percent error in the measurement of head (H) how much error in discharge measurement would occur?

(a) 3.75 percent

(b) 2.25 percent

(c) 1.50 percent

(d) 1.22 percent

Q7. A sewer is commonly designed to attain self-cleansing velocity at

(a) Sewer running half full

(b) Peak hourly rate of flow

(c) Minimum hourly rate of flow

(d) Average hourly rate of flow

Q8. When H is the flight height, R is the appropriate radial measure and d is the relief displacement the vertical height of an object appearing on an aerial photograph is

(a) dH/R

(b) R/dH

(c) RH/d

(d) H/dR

Q9. Bitumen emulsion is:

(a) Liquid containing bitumen in suspension.

(b) Paint

(c) Used as anti-corrosive paint.

(d) All the above

Q10. The rain is called as acid rain, when its pH is less than_______

(a) 3

(b) 4.5

(c) 7

(d) 8.5

SOLUTION

S1. Ans.(b)

Sol. Floor thickness,

t=h/(G-1)

h = 10 – (3 + 2) = 5 m

t=5/(2.5-1)=3.33 m.

S2. Ans.(b)

Sol. The critical velocity as per Kennedy method.

V_o=0.55 my^0.64

= 0.55 × 1.1 × (1.5)^0.64

=0.784 m/sec

S3. Ans.(c)

Sol. for floating bodies

Weight of body = weight of water displaced

γ_i×Volume =γ_sea×0.85×Vol^m of iceberg

γ_i=0.85×10.5

▭(γ_ice=8.925 kN\/m^2 )

S4. Ans.(d)

Sol.

M above G Stable equilibrium

M below G

(GM < 0) Unstable equilibrium.

M at G

(GM = 0) Neutral equilibrium

S5. Ans.(b)

Sol. equation of streamline

∂x/u=∂y/v

∂x/((-5+6x) )=∂y/((9+6y) )

ln(-5+6x)/6=ln(9+6y)/6+const

ln(-5+6x)-ln(9+6y)=const

((-5+6x))/((9+6y) )=const.

S6. Ans.(a)

Sol. discharge in V – notch –

Q = 8/15 Cd √2g H^(5/2)

Q_max = 5/2 [ΔH/H] × 100 %

= 5/2 [1.5] × 100

= 3.75 %

S7. Ans.(c)

Sol. Self-cleansing velocity is such flow velocity as would be sufficient to flush out any deposited solids in the sewer. A sewer is commonly designed to attain the self-cleansing velocity at minimum hourly rate of flow.

S8. Ans.(a)

Sol. Relief displacement is given as-

▭(d=Rh/H)

Vertical height ▭((h)=dH/R)

Where d = relief displacement

H = flying height

R = Radial distance

S9. Ans.(a)

Sol. Bitumen emulsion a liquid containing bitumen in suspension. It is used for surface dressing; patch repair works and maintenance in rainy season.

S10. Ans.(b)

Sol. the rain is called as acid rain, when its pH is less than 4.5. then main cause of acid rain is Sulphur oxides (SOx) and Nitrogen oxides (NOx).