SSC-JUNIOR ENGINEER (Civil & Structural) Online Exam 2016

Paper-I

Total Questions: 50

41. Apart from inertial force, which of the following forces is most important in motion of submarines under water?

Correct Answer: A. Viscous force
Solution:A submarine is a water craft which can be assumed to be the combination of geometrical shapes like hemisphere, cone and cylinder. The nose and tail of the submarine can be a hemisphere or cone and the body of the submarine is cylindrical. All the components of submarine are streamlined. It is capable of independent operations underwater.

Apart from inertial force, viscous forces is most important in motion of submarines under water. Submarine under water feels a resistance force against motion when it moves forward by the motion of propeller.

The forces are lift and drag which can be defined as:- A body moving with velocity "V" in a fluid making some angle with the stream line of the fluid flow experiences a force "F" acting on the body.

The component of the force along the stream line is called the DRAG and the component of the force orthogonal to the stream line is called the LIFT. The drag and lift forces are expressed in terms of co-efficient of drag and lift respectively. The co-efficient is defined as the ratio of corresponding forces to the dynamic forces on the projected areas or the planform areas.

42. When an ideal fluid flows past a sphere ___________.

Correct Answer: D. total drag is zero
Solution:Flow Past a Source

When a uniform flow is added to that due to a source:
fluid emitted from the source is swept away in the downstream direction.
stream function and velocity potential for this flow will be the sum of those for uniform flow and source.

43. Which of the following fluids can be classified as non-Newtonian?

Correct Answer: B. Human blood and. Toothpaste
Solution:A non-Newtonian fluid is a fluid that does not follow Newton's Law of Viscosity. Most commonly, the viscosity of non-Newtonian fluids is dependent on shear rate or shear rate history. Some non-Newtonian fluids with shear independent viscosity, however, still exhibit normal stress-differences or other non-Newtonian behaviuor.

Many salt solutions and molten polymers are non-Newtonian fluids, as are many commonly found substances such as ketchup, custard, toothpaste, starch suspensions, maizena, paint, blood, and shampoo.

44. In the selection of turbine by specific speed or head, which one of the following statements is not correct?

Correct Answer: A. For specific speed 10-35, Kaplan turbines

45. The field irrigation requirement is computed as __________.

Correct Answer: B. Net irrigation requirement + field application losses
Solution:Net irrigation water requirement (NIWR) is the quantity of water necessary for crop growth. It is expressed in millimetres per year or in m³/ha per year (1 mm = 10 m³/ha). It.depends on the cropping pattern and the climate. Information on irrigation efficiency is necessary to be able to transform NIWR into gross irrigation water requirement (GIWR), which is the quantity of water to be applied in reality, taking into account water losses.

Field Irrigation Requirement (FIR): It is the amount of water required to be applied to the field

FIR = NIR + water application to the field = NIR/Ea
Where, Ea = Water application efficiency.

46. Rainfall hyetograph shows the variation of _________.

Correct Answer: B. Rainfall intensity with time
Solution:

Fig.: Rainfall hyetograph and associated runoff hydrograph.

A hyetograph is a graph of rainfall intensity on the vertical axis vs. time on the horizontal axis, as shown in Fig. A hyetograph shows the volume of precipitation at any given time as the area beneath the curve, and the time-variation of the intensity.

It can be a synthetic hyetograph or an historic storm hyetograph. When a frequency or recurrence interval is specified for the input hyetograph, it is assumed that the resulting output runoff has the same recurrence interval.

47. Due to slipping of the wheels the rail forms _________.

Correct Answer: A. Crushed head
Solution:No explanation given in the book

48. On horizontal curve, if the pavement is kept horizontal across the alignment, the pressure on the outer wheels will be _________.

Correct Answer: A. more than the pressure under inner wheels
Solution:If the road surface is kept horizontal across the alignment, the pressure on the outer wheels will be higher due to the centrifugal force acting outwards and hence the reaction at the outer wheel would be higher. Thus, on horizontal curve, if the pavement is kept horizontally across the alignment, then the pressure on the outer wheels will be more than inner wheel.

49. Anaerobic treatment is best suited for _________.

Correct Answer: D. Strong organic wastes
Solution:Anaerobic treatment is applied to strong organic wastes such as those from food production and processing and the conditions of treatment help to reduce pathogens that may be present.

It can be used for meat and other protein-containing wastes which are not composted due mainly to the risk of vermin. It is carried out in a sealed container and the gas collected from the top. The methane may be burned as a fuel for heating or power generation and the residual product is reduced in volume: it can be spread on land, incinerated or disposed of in a landfill site.

Alternatively, waste that has a high organic content can be incinerated directly in a furnace to produce heat which may be used directly or to raise steam for use in power generation.

50. Pollutant Standards Index (PSI) value in between 101-199 denotes the air quality as _________.

Correct Answer: C. unhealthy
Solution:The Pollutant Standards Index, or PSI, is a type of air quality index, which is a number used to indicate the level of pollutants in air. The PSI considers six air pollutants - sulphur dioxide (SO₂), particulate matter (PM₁₀), fine particulate matter (PM₂.₅), nitrogen dioxide (NO₂), carbon monoxide (CO) and ozone (O3).

PSI Levels and Health Effects

PSIDescriptorGeneral Health Effects
0–50GoodNone
51–100ModerateFew or none for the general population
101–200UnhealthyEveryone may begin to experience health effects; members of sensitive groups may experience more serious health effects. Advised to stay indoors.
201–300Very UnhealthyHealth warnings of emergency conditions. The entire population is more likely to be affected.
301+HazardousHealth alert: everyone may experience more serious health effects.