UPSC Civil Engineering PYQs 2021 | Vaidra

1Medium15 marks

A submarine can be assumed to have cylindrical shape with rounded nose. Assuming its length to be 55 m and diameter 6.0 m, determine the total power required to overcome boundary friction if it propels at the velocity of 8.0 m/s in sea water at 20 degrees C. Take mass density of sea water at 20 degrees C as 1030 kg/m3 and kinematic viscosity of sea water at 20 degrees C as 1 x 10^-6 m2/s.

2Medium20 marks

Two settling tanks - one rectangular, with length to width ratio of $3 : 1$ and side water depth of 3.5 m; and the other circular, with side water depth of 4.0 m - are to be designed to treat $20,000\text{ m}^3\text{/d}$ of water required for a city's water supply. The surface overflow rate for satisfactory removal of solids is 20 m/d. Determine the dimensions of the settling zone of the two tanks. Check for retention time, horizontal velocity and weir overflow rate which should respectively be 3–5 hours, less than 10 m/h and 6 to $10\text{ m}^3\text{/h per m}$. Also determine the overall dimensions of the basins keeping length of inlet zone and outlet zone equal to the side water depth of the basin.

3Medium15 marks

A $0.5\text{ m}$ diameter well fully penetrates an unconfined aquifer whose bottom is 150 m below the undisturbed ground water table. When pumped at a steady rate of $6.0\text{ m}^3\text{/min}$, the drawdowns observed in two observation wells at radial distances of 10 m and 50 m are respectively 10 m and 5 m. Determine the drawdown in the well.

Civil Engineering UPSC PYQ 2021

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