Set 1 Part 1 by Pana Academy NEC Civil License

11) The drainage provided to escape water from water logged area is
(a) Surface drainage
(b) Subsurface drainage
(c) Deep drainage
(d) All of the above

Option d

12) A 180-degree elbow pipe of diameter 180Mm discharging water at 0.15 m³/s Inlet and outlet pressure are200Kpa and 195Kpa. The force exerted by water at the bend is

(a) 127N
(b) 128N
(c) 125N
(d) 127.8N

$$\begin{aligned} &\text{Option a} \\ &\mathrm{Diameter~of~pipe}=0.18\mathrm{m} \\ &\mathrm{C/S~Area~(A)=\frac{\pi}{4}*0.18^{2}=0.0254m^{2}} \\ &\mathrm{Discharge} (Q)=0.15\mathrm{m}^{3}/\mathrm{s} \\ &\mathrm{Velocity~at~section~1~and~2~(V_{1},V_{2})=\frac{Q}{A}=5.9m/s} \\ &\mathrm{Pressure~at~section~1(P_{1})=200Kpa} \\ &\mathrm{Pressure~at~section~2(P_{2})=195Kpa} \\ &\mathrm{Angle~of~bend}\left(\theta\right)=180^{\circ} \\ &\mathrm{Resultant~force~(F_{R})=?} \\ &\text{Direction of resultant force=?} \\ &\sum F_{x}=\rho Q(V_{2x}-V_{1x}) \\ &(P_{1}A_{1}-P_{2}A_{1})-F_{x}=\rho Q(V_2-V_{1}) \\ &F_{x}= (P_{1}A_{1}-P_{2}A_{1})+\rho Q(V_{2}-V_{1}) \\ &=(200000*0.0254-195000*0.0254)+1000*0.45(5.9-5.9) \\ &=127 N \\ &\sum F_{y}=\rho Q(V_{2y}-V_{1y}) \\ &\text{Neglecting weight} \\ &\mathrm{F_{y}=0} \\ &\mathrm{Resultant~force~(F_{R})=~\sqrt{\left(F_{x}^{2}+F_{y}^{2}\right)^{2}}=127~N} \end{aligned}$$

13) A nozzle discharging water into the stationary plate, the force exerted on plate
is
(a) 𝜌 ∗ 𝐴 ∗ 𝑄
(b) 𝜌 ∗ 𝐴 ∗ 𝑉
(c) 𝜌 ∗ \(𝑉^2\)
(d) 𝜌 ∗ 𝑉 ∗ 𝑄

Option d

14) The maximum vertical clearance in hill road for overhanging cliff is
(a) 3m
(b) 4m
(c) 5m
(d) 6m

Option c

According to NRS 2070, a vertical clearance of 5.0m measured from the crown of the road surface shall be provided for whole roadway widths on all roads. No obstructions shall be made on this
space.

15) The sieve size used in Los Angle Abrasion test is
(a) 1.7 mm
(b) 2.36 mm
(c) 1.77 mm
(d) 1.5 mm

Option a

Sieves: IS Sieves with the following mesh sizes are available – 1.70mm, 2.36mm, 4.75mm, 6.3mm, 10mm, 12.5mm, 20mm, 25mm, 40mm, 50mm, 63mm, and 80mm.

Aggregate Abrassion Value = ((A-B)/A) X 100

where,
A = weight in gm of oven-dried sample.
B = weight in gm of fraction retained on 1.70 mm IS Sieves after washing and oven-dried upto constant weight.

Also, LA abrasion value = wt passes through no 12 (1.70mm) sieve/ total wt *100