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*315. The time required to empty a concrete tank through a rectangular weir at the side from a head of 16 cm to 8 cm over the crest was found to be 16 minutes. The time required to empty it further up to the crest will be a) 16 minutes b) 24 minutes c) 256 minutes d) infinite 931?
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*315. The time required to empty a concrete tank through a rectangular...
Solution:
Given data:
Head at the start of emptying = 16 cm
Head at the end of emptying = 8 cm
Time taken to empty the tank = 16 minutes
To find:
Time required to empty the tank up to the crest
Assumptions made:
The flow through the rectangular weir is steady and incompressible.
The cross-section of the tank remains the same throughout the emptying process.
Calculation:
Let Q1 be the discharge through the rectangular weir when the head is 16 cm.
Let Q2 be the discharge through the rectangular weir when the head is 8 cm.
Let t1 be the time taken to empty the tank from 16 cm to 8 cm.
Let t2 be the time required to empty it further up to the crest.
From the Francis formula, we know that:
Q = CLH^1.5
where Q = discharge, C = coefficient of discharge, L = length of the weir crest, and H = head over the crest.
Since the crest length remains the same, we can write:
Q1 = CL(16)^1.5
Q2 = CL(8)^1.5
Dividing the two equations, we get:
Q1/Q2 = (16/8)^1.5
Q1/Q2 = 2.828
We also know that:
Q = AV
where A = area of cross-section of the tank and V = velocity of water.
Since the cross-sectional area remains the same, we can write:
Q1 = AV1
Q2 = AV2
Dividing the two equations, we get:
Q1/Q2 = V1/V2
Using the continuity equation, we know that:
A1V1 = A2V2
Substituting the above equation in the previous equation, we get:
Q1/Q2 = A2/A1
Since the cross-sectional area remains the same, we can write:
Q1/Q2 = 1
Comparing this with the previous result, we get:
2.828 = 1
This is not possible, which means our assumption that the cross-sectional area remains the same is wrong.
Therefore, the time required to empty the tank up to the crest is infinite.
Answer: d) infinite.
Given data:
Head at the start of emptying = 16 cm
Head at the end of emptying = 8 cm
Time taken to empty the tank = 16 minutes
To find:
Time required to empty the tank up to the crest
Assumptions made:
The flow through the rectangular weir is steady and incompressible.
The cross-section of the tank remains the same throughout the emptying process.
Calculation:
Let Q1 be the discharge through the rectangular weir when the head is 16 cm.
Let Q2 be the discharge through the rectangular weir when the head is 8 cm.
Let t1 be the time taken to empty the tank from 16 cm to 8 cm.
Let t2 be the time required to empty it further up to the crest.
From the Francis formula, we know that:
Q = CLH^1.5
where Q = discharge, C = coefficient of discharge, L = length of the weir crest, and H = head over the crest.
Since the crest length remains the same, we can write:
Q1 = CL(16)^1.5
Q2 = CL(8)^1.5
Dividing the two equations, we get:
Q1/Q2 = (16/8)^1.5
Q1/Q2 = 2.828
We also know that:
Q = AV
where A = area of cross-section of the tank and V = velocity of water.
Since the cross-sectional area remains the same, we can write:
Q1 = AV1
Q2 = AV2
Dividing the two equations, we get:
Q1/Q2 = V1/V2
Using the continuity equation, we know that:
A1V1 = A2V2
Substituting the above equation in the previous equation, we get:
Q1/Q2 = A2/A1
Since the cross-sectional area remains the same, we can write:
Q1/Q2 = 1
Comparing this with the previous result, we get:
2.828 = 1
This is not possible, which means our assumption that the cross-sectional area remains the same is wrong.
Therefore, the time required to empty the tank up to the crest is infinite.
Answer: d) infinite.
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*315. The time required to empty a concrete tank through a rectangular weir at the side from a head of 16 cm to 8 cm over the crest was found to be 16 minutes. The time required to empty it further up to the crest will be a) 16 minutes b) 24 minutes c) 256 minutes d) infinite 931?
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*315. The time required to empty a concrete tank through a rectangular weir at the side from a head of 16 cm to 8 cm over the crest was found to be 16 minutes. The time required to empty it further up to the crest will be a) 16 minutes b) 24 minutes c) 256 minutes d) infinite 931? for Civil Engineering (CE) 2024 is part of Civil Engineering (CE) preparation. The Question and answers have been prepared according to the Civil Engineering (CE) exam syllabus. Information about *315. The time required to empty a concrete tank through a rectangular weir at the side from a head of 16 cm to 8 cm over the crest was found to be 16 minutes. The time required to empty it further up to the crest will be a) 16 minutes b) 24 minutes c) 256 minutes d) infinite 931? covers all topics & solutions for Civil Engineering (CE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for *315. The time required to empty a concrete tank through a rectangular weir at the side from a head of 16 cm to 8 cm over the crest was found to be 16 minutes. The time required to empty it further up to the crest will be a) 16 minutes b) 24 minutes c) 256 minutes d) infinite 931?.
*315. The time required to empty a concrete tank through a rectangular weir at the side from a head of 16 cm to 8 cm over the crest was found to be 16 minutes. The time required to empty it further up to the crest will be a) 16 minutes b) 24 minutes c) 256 minutes d) infinite 931? for Civil Engineering (CE) 2024 is part of Civil Engineering (CE) preparation. The Question and answers have been prepared according to the Civil Engineering (CE) exam syllabus. Information about *315. The time required to empty a concrete tank through a rectangular weir at the side from a head of 16 cm to 8 cm over the crest was found to be 16 minutes. The time required to empty it further up to the crest will be a) 16 minutes b) 24 minutes c) 256 minutes d) infinite 931? covers all topics & solutions for Civil Engineering (CE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for *315. The time required to empty a concrete tank through a rectangular weir at the side from a head of 16 cm to 8 cm over the crest was found to be 16 minutes. The time required to empty it further up to the crest will be a) 16 minutes b) 24 minutes c) 256 minutes d) infinite 931?.
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