Which of the following statements is/are true? i. The specific energy curve is a curve that shows the variation of specific energy with respect to time. ii. Critical depth of flow is that of flow at which the specific energy is minimum.
- AOnly (i)
- BOnly (ii)Correct
- CBoth (i) and (ii)
- DNeither (i) nor (ii)
Solution
Concept
Specific energy and critical flow depth
Formula
NONE
Step-by-step solution
1. The specific energy curve shows variation of specific energy with respect to depth of flow for a given discharge, not time, making statement i false. 2. Critical depth is defined as the depth of flow at which specific energy is at its minimum for a given discharge, making statement ii true. Answer: B
Explanation
The specific energy curve illustrates how specific energy varies with flow depth for a constant discharge, not time, making statement i false. Critical depth is defined as the flow depth at which the specific energy is at its minimum value for a given discharge. Therefore, option B is correct.
Why the other options are wrong
A) Statement (i) is false because specific energy varies with flow depth rather than time. C) Statement (i) is incorrect, making both statements together an invalid option. D) Statement (ii) is true as critical depth minimizes specific energy for a given flow rate.
Shortcut
Specific energy curve plots energy against depth (not time); critical depth gives minimum specific energy.
Common mistake
Selecting option C by believing specific energy varies with time rather than with flow depth.
Correct answer: B) Only (ii)