250+ TOP MCQs on Flow through Large Orifice and Answers

Fluid Mechanics Multiple Choice Questions on “Flow through Large Orifice”.

1. 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
Answer: a
Clarification: It is the correct parametric definition for ‘large orifice’.

2. In case of any orifice, velocity always remains constant and hence discharge can be calculated.
a) True
b) False
Answer: b
Clarification: In case of large orifice, velocity always remains variable and hence discharge cannot be calculated.

3. 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
Answer: a
Clarification: Q = 2/3 Cd *b*√2g* (H2^1.5 – H1^1.5)
Here,
H1 = 3.8
H2 = 2.5
b = 2.2
Hence, Q = 13.9 m³/s.

4. 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
Answer: a
Clarification: Q = 2/3 Cd *b*√2g* (H2^1.5 – H1^1.5)
Here,
H1 = 5
H2 = 3.3
b = 3.2
Hence, Q = 29.4 m³/s.

5. 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
Answer: a
Clarification: Q = Cd * b * (H2 – H1) √2gH
Here, b = 2.3
H2 = 2.75
H1 = 2.6
H = 40
Q = .56 m³/s.

6. 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
Answer: a
Clarification: Q = Cd * b * (H2 – H1) √2gH
Here, b = 3.3
H2 = 2.67
H1 = 2.25
H = 50
Q = 2.6 m³/s.

7. 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
Answer: a
Clarification: Clarification: Q = Cd * b * (H2 – H) √2gH
Here, b = 2
H2 = 4.2

H = 3.5
Q = 4.94 m³/s.