Engineering Questions with Answers - Multiple Choice Questions

# MCQs on Classification of Orifice & Hydraulic Coefficients

1 - Question

When is orifice called ‘large orifice’?
a) If the head of liquid is less than 5 times the depth of orifice
b) If the head of liquid is less than 2.5 times the depth of orifice
c) If the head of liquid is less Hence, 4 times the depth of orifice
d) If the head of liquid is less than 1.5 times the depth of orifice

a
Explanation: It is the correct parametric definition for ‘large orifice’.

2 - Question

In case of any orifice, velocity always remains constant and hence discharge can be calculated.
a) True
b) False

b
Explanation: In case of large orifice, velocity always remains variable and hence discharge cannot be calculated.

3 - Question

Find the discharge through a rectangular orifice 2.2 m wide and 1.3 m deep fitted to a easier tank. The water level in a team is 2.5 m above the top edge of orifice.
a) 13.9 m3/s
b) 11.5 m3/s
c) 16.9 m3/s
d) 8.7 m3/s

a
Explanation: Q = 2/3 Cd *b*√2g* (H21.5 – H11.5)
Here,
H1 = 3.8
H2 = 2.5
b = 2.2
Hence, Q = 13.9 m3/s.

4 - Question

Find the discharge through a rectangular orifice 3.2 m wide and 1.7 m deep fitted to a easier tank. The water level in a team is 3.3 m above the top edge of orifice. Take Cd = 0.6
a) 29.4 m3/s
b) 58.5 m3/s
c) 67.9 m3/s
d) 78.7 m3/s

a
Explanation: Q = 2/3 Cd *b*√2g* (H21.5 – H11.5)
Here,
H1 = 5
H2 = 3.3
b = 3.2
Hence, Q = 29.4 m3/s.

5 - Question

Find the discharge through totally drowned orifice of width 2.3 m if the difference of water levels on both side of the orifice be 40 cm. The height of water from to and bottom of the orifice are 2.6 m and 2.75 m respectively.
a) .56 m3/s
b) .64 m3/s
c) .75 m3/s
d) .55 m3/s

a
Explanation: Q = Cd * b * (H2 – H1) √2gH
Here, b = 2.3
H2 = 2.75
H1 = 2.6
H = 40
Q = .56 m3/s.

6 - Question

Find the discharge through totally drowned orifice of width 3.3 m if the difference of water levels on both side of the orifice be 50 cm. The height of water from to and bottom of the orifice are 2.25 m and 2.67 m respectively.
a) 2.8 m3/s
b) 2.7 m3/s
c) 2.6 m3/s
d) 2.5 m3/s

a
Explanation: Q = Cd * b * (H2 – H1) √2gH
Here, b = 3.3
H2 = 2.67
H1 = 2.25
H = 50
Q = 2.6 m3/s.

7 - Question

A rectangular orifice of 2 m width and 1.2 m deep is fitted in one side of large tank. The easier level on one side of the orifice is 3m above the top edge of the orifice while on the other side of the orifice the water level is 0.5 m below it’s top edge. Calculate discharge if Cd = .64
a) 4.95 m3/s
b) 5.67 m3/s
c) 3.56 m3/s
d) 6.75 m3/s

a
Explanation: Explanation: Q = Cd * b * (H2 – H) √2gH
Here, b = 2
H2 = 4.2
H = 3.5
Q = 4.94 m3/s.

8 - Question

The time taken to empty the tank is independent of Cd but depends only on the height and acceleration due to gravity.
a) True
b) False

b
Explanation: The time taken to empty the tank is dependent on Cd as well as depends only on the height and acceleration due to gravity.

9 - Question

The discharge rate is independent of the height difference and dependent only on the height.
a) True
b) False

b
Explanation: The discharge rate is dependent of the height difference and dependent only on the height.

10 - Question

In case of submerged orifice the discharge is substantially dependent on temperature of fluid
a) True
b) False