Question

Questions 1-2. DIRECTIO!IS: Questions 1 and 2 refer to the vertical curve shown below. Trop reck60salt cr a Simla, dark gheeus rock 04% +0.9% EL 2245 A 19.-9.110t0.412 1.. The algebraic difference in gradient between the two slopes is A. 0.6 1. +1.2% C. +1.0% D. B. -0.8% The elevation of point X on the curve is B. 23.25 2. D. 23.95 C. 23.55 A. 22.80 STA 20129 STA STA 0o+80

Answer 1

Ans 1) We know,

Difference in elevation , A = G1 - G2

= 0.8 - (-0.4)

1.2 %

Hence option D is correct

Ans 2) We know,

y = ax² + bx + c

where, y = roadway elevation from beginning of vertical curve

a = (G2 - G1) / 2L = -1.2 / (2 x 6) = -0.10 ( L = 58 - 52 = 6 ft)

b = G1

c = elevation of PVC = 22.45

x = distance of point X from beginning of vertical curve = 55 - 52 = 3 ft

Putting values,

y = -0.10(3)² + 0.8(3) + 22.45

= - 0.9 + 2.4 + 22.45

= 23.95

Hence option D is correct

Ans 7) Option B is correct as per shown figure

Ans 10) Weight per foot for C 8 x 11.5 = 11.5 lb

Density of steel = 490 lb/ft³ or 0.283 lb/in³

We know, $\dpi{100} \rho$ = M / V

=> 0.283 = 11.5 / V

=> V = 40.63 in³

Also, V = A x h

For length (h) = 1 ft = 12 in,

A = 40.63 in³ /12 in

=> A = 3.38 in²

Hence, option C is correct

Ans) Total hydro static pressure acting on sluice gate = Area of trapezium formed by pressure diagram x $\dpi{100} \gamma$ _w  

= 0.5 x (15 + 21) (6) x 62.4 (Unit weight of water ,$\dpi{100} \gamma$_w= 62.4 lb /ft³)

= 1123.2 psf

Area of sluice gate = 4 x 6 = 24 ft²

Hydrostatic force = Pressure x area = 1123.2 x 24 = 26956 lb $\dpi{100} \approx$ 27000 lb   

Hence, option C is correct

Ans 24) Given ,

P = f_c [ 1 + (n -1) P_o ]

P_o = (1 - 0.01) x 20 = 19.8 in²

=> P = 500[ 1 + 14(19.8)]

P = 139100 lb $\dpi{100} \approx$ 175000 lb

Hence, option A is correct

Ans) Option D is correct, because settlement in sewer by 6 in will cause vaporization of liquid due to pressure drop which result in cavitation