Civil Engineering Test | QA 007

Friends !

Let me first give you the answers of problems given on last Sunday.

Q 01: A Seattle bound plane departs Dubai at 8.30 A.M on 9th April and takes 14 and a half hour to arrive Seattle. What is the local time and date of arrival of this plane at Seattle, ignoring DST, if longitudes of Dubai and Seattle are 56° E and 124° W respectively.

Ans: Longitude difference between Dubai and Seattle = ((56 - (-124))

= 180° W of Dubai.
15° difference in longitude

= 1 hour difference
180° difference in longitude

= 180/15 = 12 hours difference
Since, Seattle is west of Dubai, Seattle time will be 12 hours back of Dubai.
The plane departed Dubai at Dubai time 8.30 A.M on 9th April.
This means the plane departed Dubai at Seattle time 8.30 P.M on 8th April.
Add 14 hours 30 min fly time -
Arrival time and date at Seattle

= 8.30+14.30-12

= 11.00 A.M on 9th April. 

Q 02: Find out the volume of a 1.8 m high stack of stone chips, stored in the shape of a truncated pyramid, if it's bottom length x width is 5.0 m x 4.0 m and top length x width is 2.5 m x 2.0 m.

Ans: Volume V = H(A+B+√(AB))/3, where
H = Height of stack = 1.8 m
A = Area of bottom surface = 5 x 4 = 20 sqm
B = Area of top surface = 2.5 x 2 = 5 sqm
Hence Volume = 1.8 x (20+5+√(20 x 5))/3

= 21 cum.

Q 03: The factory length of a 25 mm dia tor bar is normally 12.2 m. How many pieces of such bars are required to purchase a minimum of 1 M/T steel ?

Ans: Unit weight of steel = 7,850 kg/cum
Weight of 12.2 m long 25 mm dia steel bar

= 12.2 x (3.1416 x 0.025 x 0.025/4) x 7,850

= 47 kg.
No. of bar required to purchase minimum

1 M/T steel = 1000/47

= 21.276 = 22 Nos.

Q 04: The reading of a levelling staff placed on a B.M of R.L 123.50 m was 1.40 m. The same was 1.6 m when placed inverted beneath the ceiling of a roof. What is the R.L of the top of the roof if roof thickness is 0.1 m.

Ans: R.L of roof top = 123.5 + 1.4 + 1.6 + 0.1

= 126.6 m.

Q 05: A point load of 15 KN is acting at a distance of 2 m from left support of a 6 m long simply supported beam. What is the maximum reaction and bending moment ?

Ans: Since the load is nearer to left support, maximum reaction will be at left support.
R(left) = (6-2) x 15/6 = 10 KN
R(right) = 15-10 = 5 KN
Max BM at load point = 10 x 2 = 20 KN.

Q 06: What is the material cost of 1 cum plain cement concrete of volumetric proportion 1:2.5:4 if rate of cement is Rs.400/ per bag, rate of sand is Rs.3,200/ per cum and rate of stone chips is Rs.5,000/ per cum ?

Ans: For 1 cum concrete,

dry volume of materials = 1.5 cum
For volumetric proportion of materials 1:2.5:4,
Cement = 1 x 1.5/(1+2.5+4)

= 0.2 cum = 0.2 x 30 = 6 bags
Sand = 2.5 x 1.5/(1+2.5+4) = 0.5 cum
Stone chips = 4 x 1.5/(1+2.5+4) = 0.8 cum
Material cost

= 6 x 400 + 0.5 x 3200 + 0.8 x 5000

= Rs. 8,000/

Q 07: A two span continuous beam of  span length L each is carrying a uniformly distributed load of w per unit length through out the entire beam. Find out the support reactions.

Ans: This problem can be best solved by the method of consistent deformation.
Releasing the mid-support temporarily and applying uniformly distributed load -
Mid-span deflection (downward)
= (5/384EI) x w x (2L^4)
= (5/24EI) x wL^4 ........ (1)
Now applying an upward mid-span reaction Rm and releasing uniformly distributed load
Mid span deflection (upward)
= (1/48EI) x Rm x (2L^3) ....... (2)
Equating equations 1 and 2, we get
Rm = (5/4) wL = 1.25 wL
Total load = 2 wL
Reactions at left and right supports
= (2 wL - 1.25 wL)/2 = 0.375 wL

Q 08: Find out the number of sleepers required for laying 520 m long broad gauge railway track with a sleeper density of (N+5).

Ans: Standard Length of BG Rail = 13 m
Number of Rail Reqd = 520/13 = 40
Sleeper density = N+5 = 13+5 = 18
Number of sleeper = 40 x 18 = 720

Q 09: A certain waste has a BOD of 200 mg/liter and its flow is 1,000 cum per day. If the domestic sewage has a BOD of 100 gm per capita, what is the population equivalent of the waste ?

BOD of waste = 200 mg/liter
= 0.2 gm per liter = 200 gms/cum
Daily BOD = 200 x 1000 gms
Population Equivalent
= 200 x 1000/100 = 2000

Q 10: How much area in square feet and square metre is equal to an acre ?
Ans: 1 chain = 66 ft
1 acre = 1 chain x 10 chain
= 66 x 10 x 66 = 43,560 sft
= 43,560/10.76 = 4048 sqm

So, these are the answers of the problems given in last week. To create your interest further,  I'm now giving some more problems with answers. Try these. Write to me if any case of any difficulty.

Q 01: A simply supported beam with overhangs in both ends is subjected to a uniformly distributed load of w per unit length throughout the entire beam. If the main span length is L and overhang lengths are 0.5L each, what is bending moment at the center of the beam?

A. 0.5 x (wL^2)

B. 0.25 x (wL^2)

C. 0.125 x (wL^2)

D. Zero 

Q 02: Under adequate tension, a 25 mm dia bar elongates 0.1 mm over a gauge length of 150 mm. At the same time, the diameter of the bar decreases by 0.005 mm. Find out the Poisson's ratio of the bar.
A. 0.3
B. 0.03
C. 0.003
D. 0.0003

Q 03: When water is mixed with cement -

A. Endothermic chemical reaction happens

B. Exothermic chemical reaction happens

C. Endothermic physical action happens

D. Exothermic physical action happens

Q 04: As per IS Code of Practice for Reinforced Concrete Design, IS 456, the short term static modulus of concrete is assumed as

A. 4000 √(fck)

B. 5000 √(fck)

C. 5500 √(fck)

D. 6500 √(fck)

Q 05: Levelling across a river is done by

A. Invert levelling

B. Trigonometric levelling

C. Reciprocal levelling

D. Fly levelling

Q 06: The most suitable cement (among the following) for construction of road pavement is

A. Ordinary Portland Cement

B. Low Heat Cement

C. Rapid Hardening Cement

D. Blast Furnace Slag Cement

Q 07: As per Indian Roads Congress regulation, the carriage way for single lane road is

A. 3.75 m

B. 3.50 m

C. 3.25 m

D. 3.00 m

Q 08: The intensity of pressure at a point in a fluid is 4.905 N/sq cm. Accordingly, find the height of fluid if the fluid is (a) water (b) an oil with specific gravity 0.8.

A. 4.00 m and 5.00 m

B. 5.00 m and 6.25 m

C. 4.00 m and 6.25 m

D. 5.00 m and 6.00 m

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.Answers

1. D  2. A  3. B  4. B  5. C

6. C  7. A  8. B

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