QUIZ : CIVIL ENGINEERING (30-12-2020)

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

Each question carries 1 mark
Negative marking: 1/4 mark
Time: 10 Minutes

Q1. If Poisson’s ratio for a material is 0.5, then the elastic modulus for the material is
(a) three times its shear modulus
(b) four times its shear modulus
(c) equal to its shear modulus
(d) indeterminate
Q2. The Poisson’s ratio of a material which has Young’s modulus of 120 GPa, and shear modulus of 50 GPa, is
(a) 0.1
(b) 0.2
(c) 0.3
(d) 0.4
Q3. Solid uniform metal bar of diameter D and length L is hanging vertically from its upper end. The elongation of the bar due to self weight is
(a) Proportional to L and inversely proportional to D²
(b) Proportional to L² and inversely proportional to D²
(c) Proportional to L but independent of D
(d) Proportional to L² but independent of D
Q4. True stress σ is related with conventional stress σ_0 as
(a) σ/σ_0 =(1+ϵ)^2
(b) 〖σ/σ〗_0=1/(1+ϵ)^2
(c) 〖σ/σ〗_0=1/(1+ϵ)
(d) σ/σ_0 =1+ϵ
Q5. The radius of Mohr’s circle of stress of a strained element is 20 mm and minor principal tensile stress is 10 N/mm². The major principal stress is
(a) 30 N/mm²
(b) 50 N/mm²
(c) 60 N/mm²
(d) 100 N/mm²
Q6. The principal stresses σ_1,σ_2 and σ_3 at a point respectively are 80 MPa, 30 MPa and – 40 Mpa. The maximum shear stress is
(a) 25 MPa
(b) 35 MPa
(c) 55 MPa
(d) 60 MPa
Q7. According to IS classification, the range of silt size particles is
(a) 4.76 mm to 2.0 mm
(b) 2.00 mm to 0.425 mm
(c) 0.425 mm to 0.075 mm
(d) 0.075 mm to 0.002 mm
Q8. The plasticity index and the percentage of grain size finer than 2 microns of a clay sample are 25 and 15, respectively, its activity ratio is
(a) 2.5
(b) 1.67
(c) 1.0
(d) 0.6
Q9. An undisturbed soil sample has a plastic limit of 25%, a natural moisture content of 40% and liquidity index of 50%. It liquid limit in % will be
(a) 50
(b) 55
(c) 60
(d) 75
Q10. A soil mass contains 40% gravel, 50% sand and 10%, silt. This soil can be classified as
(a) silty sandy gravel having coefficient of uniformity less than 60.
(b) silty gravelly sand having coefficient of uniformity equal to 10.
(c) gravelly silty sand having coefficient of uniformity greater than 60
(d) gravelly silty sand and its coefficient of uniformity cannot be determined.

Solutions

S1. Ans.(a)
Sol. E=2G(1+μ)
E=2G(1+0.5)
▭(E=3G)

S2. Ans.(b)
Sol. E=120 GPa
G=50 GPa

    E=2G(1+μ)
    120=2×50(1+μ )

       1+μ=120/100
       ▭(μ=0.2)  

S3. Ans.(d)
Sol. Elongation of bar due to self weight
▭(∆L=(YL^2)/2E)
▭(∆L α L^2 )

S4. Ans.(c)
Sol. ▭(σ/σ_0 =1/(1+ϵ))
σ- true stress
σ_0-conventional stress
ϵ=strain

S5. Ans.(b)
Sol. Radius of mohr circle =(σmax-σmin)/2
20=(σmax-10)/2
▭(σmax=50N\/mm^2 )

S6. Ans.(d)
Sol. σ_1=80 MPa
σ_2=30 MPa
σ_3=-40 MPa
Maximum shear stress =(σ_1-σ_3)/2
=(80-(-40))/2
=60MPa

S7. Ans.(d)
Sol. Gravel → 4.75 to 80mm
Sand → 0.075 to 4.75mm
Silt → 0.002 to 0.075mm
Clay → <0.002mm

S8. Ans.(b)
Sol. Activity =I_p/C
I_p- Plasticity index
C- percentage of clay particle
Activity =25/15=1.67.

S9. Ans.(b)
Sol. w_p=25%
w=40%
I_L=50%
w_L=?
Liquidity index 〖(I〗_L)=(w-w_p)/(w_L-w_p )
50=(40-25)/(w_L-25)
▭(W_L=55%)

S10. Ans.(c)
Size Soil % Retained Cumulative % N=100-cumulative
4.75 Gravel 40% 40% 60%
0.075 Sand 50% 90% 10%
0.002 Silt 10% 100% 0%
Coefficient of uniformity (Cu)=D60/D10
=4.75/0.075
=63.33

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