Quiz: Civil Engineering

Exam: DFCCIL EXECUTIVE

Topic: MISCELLANEOUS

Each question carries 1 mark

Negative marking: 1/4 mark

Time: 10 Minutes

Q1. The height of hydraulic jump is equal to:

(a) Sequent depth

(b) Difference in conjugate depths

(c) Difference in alternate depths

(d) Initial depth

Q2. During the formation of hydraulic jump

(a) the specific energy and specific force remains constant

(b) the specific energy increase and specific force decreases

(c) the specific energy decrease and specific force increase

(d) the specific energy decrease and specific force remains constant

Q3. If the Froude number of a hydraulic jump is more than 9, this jump is classified as –

(a) Weak jump

(b) Strong jump

(c) Oscillating jump

(d) None of these

Q4. The sequent depth ratio of a hydraulic jump in a rectangular horizontal channel is a 10.30. The Froude number at the beginning of the jump is

(a) 5.64

(b) 7.63

(c) 8.05

(d) 13.61

Q5. For open channel, Manning’s formula with usual notations is –

(a) V = 1/N R^(1/3 ) S^(1/2 )

(b) V = 1/N R^(2/3 ) S^(1/2 )

(c) V = 1/N R^(1/3 ) S^(1/3 )

(d) None of the above

Q6. The critical depth at a section of a rectangular channel is 1.5m. The specific energy at that section is

(a) 0.75m

(b) 1.00m

(c) 1.50m

(d) 2.2m

Q7. For best triangular section the hydraulic radious should be:

(a) y

(b) y/√8

(c) y/2

(d) 2/√3 y

Q8. Cold driven rivets range from…………..

(a) 6 to 10 mm in diameter

(b) 10 to 16 mm in diameter

(c) 12 to 22 mm in diameter

(d) 22 to 32 mm in diameter

Q9. A steel member is designed with a consideration for failure governed by buckling. What should be the partial factor of safety for materials to be considered?

(a) 0.90

(b) 1.00

(c) 1.10

(d) 1.25

Q10. A steel beam is carrying just its self load. it needs to be so supported on two columns (span length, L) with equal overhangs (Y) on both the sides such that the bending moment at the mid-span is zero. The ratio of L/Y should be:

(a) 0.25

(b) 0.5

(c) 1.00

(d) 2.00

SOLUTION

S1. Ans. (b)

Sol. Height of hydraulic jump equal to difference in conjugate or sequent depth. Conjugate depth having same specific force

S2. Ans. (d)

Sol. During the formation of hydraulic jump specific energy decreases and specific force remains constant

S3. Ans. (b)

Sol. Classification of hydraulic jump –

Jump Froude Number

Undular Jump 1 to 1.7

Weak Jump 1.7 to 2.5

Oscillating Jump 2.5 to 4.5

Steady Jump 4.5 to 9

Strong Jump > 9

S4. Ans. (b)

Sol. y_2/y_1 = 10.30

y_2/y_1 = (-1+√(1+8 Fr_1^2 ))/2

10.30 = (-1+√(1+8 ×Fr_1^2 ))/2

Fr_1^2 = 7.62

S5. Ans. (b)

Sol. Mannings formula –

v=1/n R^(2/3) S^(1/2)

n → Manning Coefficient

S6. Ans. (d)

Sol. Critical depth (y_c) = 1.5m

Specific Energy (E_c) = ?

E_c = 3/2 y_c

= 3/2 × 1.5

E_c = 2.25 m

S7. Ans. (b)

Sol. For most efficient triangular channel

Hydraulic Radiaus (R) = y/(2√2)

R=y/√8

S8. Ans.(c)

Sol. Riveting is done at atmospheric temperature by large pressure such rivet called cold driven rivets. When rivet’s are heated before driving that such rivet are called hot driven rivets. Cold driven rivets are used for 12 mm to 22 mm diameter.

S9. Ans.(c)

Sol. when a steel member is designed with a consideration for failure governed by buckling then partial factor of safety should be taken as 1.10.

S10. Ans.(d)

Sol. When a steel beam is carrying just its self load and it needs to be supported on two column (span length, L) with equal overhangs (Y) on both the sides such that the bending moment at the mid span is zero, then the ratio of L/y should be 2.00.