- #1
Zouatine
- 22
- 0
- Homework Statement
- Hi everybody,
I found some difficulty to understand the following exercise and that solution,
Statement of Exercise:
Either a uniform rectangular channel of slope (i),
What are:the draft (height) (y),and the width (L) for the wet section to be minimal.
- Relevant Equations
- Aw= Area of channel= y*L,
Pw= Perimeter wet =y+2L,
My problem:
In the solution,our teacher found, that the wet section is minimal if y=L/2
So
Am: = L^2 /2;
Pm: = 2L;
So despite that I try with any value, I can not find a more minimal section,
and that's not the case because if I try with y = L / 3 I find
Am: L^2/3;
Pm: (5/3)*L ;
and these values are less than the value of y = L / 2.
so why that ? is that because I did not understand the exercise or our teacher made a mistake?
Thank you
In the solution,our teacher found, that the wet section is minimal if y=L/2
So
Am: = L^2 /2;
Pm: = 2L;
So despite that I try with any value, I can not find a more minimal section,
and that's not the case because if I try with y = L / 3 I find
Am: L^2/3;
Pm: (5/3)*L ;
and these values are less than the value of y = L / 2.
so why that ? is that because I did not understand the exercise or our teacher made a mistake?
Thank you