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DFCCIL’21 CE: Daily Practice Quiz. 28-July-2021

Quiz: Civil Engineering
Exam: DFCCIL-JE
Topic: MISCELLANEOUS

Each question carries 1 mark
Negative marking: 1/4 mark
Time: 8 Minutes

Q1. If Cv, Cc, Cd and Cr are the hydraulic coefficients of an orifice, then
(a) Cd = Cc . Cv
(a) Cr = 1 + Cv2/Cd
(c) Cv = Cc + Cd
(d) Cc = Cv/Cd

Q2. The critical depth of flow in a most economical triangular channel section for a discharge of 1 m³/sec is given by
(a) (1/9.8)^(1/5)metre
(a) (1/9.8)^(1/3)metre
(c) (1/4.9)^(1/5)metre
(d) (1/4.9)^(1/3)metre

Q3. If the velocity, bulk modulus of elasticity and the mass density of a fluid are denoted by U, K and ρ respectively, then the Mach number is given by
(a) (U√K)/√ρ
(a) (U√ρ)/√K
(c) (ρ√U)/√K
(d) (K√U)/√ρ

Q4. Poise is the unit of:
(a) Mass density
(a) Kinetic viscosity
(c) Dynamic viscosity
(d) Velocity gradient

Q5. Which one of the following methods is used for the approximate estimation?
(a) Both central line and short wall and long wall method
(b) Central line method
(c) Plinth area method
(d) Short wall and long wall method

Q6. Accuracy in the measurement of the thickness of the slab or sectional dimension of column and beam (in centimetre) should be
(a) 0.5
(b) 1
(c) 5
(d) 10

SOLUTION

S1. Ans.(a)
Sol. coefficient of discharge is defined as the ratio of the actual discharge from an orifice to the theoretical discharge from the orifice. It is denoted by C_d.

C_d=(Actual discharge)/(Theoritical discharge)
=(Actual velocity)/(Theoritical velocity)×(Actual area)/(Theoritical Area)
▭(C_d=C_v×C_C )
C_V= coefficient of velocity
C_C= coefficient of contraction.

S2. Ans.(c)
Sol. for most economical triangular channel section, the side slope m = tanθ = tan 45
▭(m=1)
Given, Q = 1 m³/sec.
Now, critical depth for triangular channel
Section –
y_c=((2Q^2)/(gm^2 ))^(1\/5)
=[(2×(1)^2)/(9.8×(1)^2 )]^(1\/5)
▭(y_c=(1/4.9)^(1\/5) metre)

S3. Ans.(b)
Sol. Mach Number = √((Intertia force)/(Elastic force))
=U/C
=U/√(K\/ρ)

S4. Ans.(c)
Sol. The unit of dynamic viscosity is (N-sec)/m^2 or poise.
1 (N-sec.)/m^2 = 10 Poise.
S5. Ans.(c)
Sol. The approximate estimate is prepared from the practical knowledge and cost of similar projects. There are some methods for the approximation estimate.
Plinth area method
Unit base method
Cubical contents method

S6. Ans.(a)
Sol. The accuracy in the measurement of the thickness of the slab or sectional dimension of column and beam should be 0.5 cm.
Wood work = 2 mm
Steel work = 1 mm
Volume = 0.01 m³
Area = 0.01 m²

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