Question

A longitudinal rectangular surface is hanged into water such that its top and bottom points are at depth of 1.5 m and 6.0 m respectively. The depth of pressure (m) from the top surface is_______.

• A. 3.8
• B. 4.2
• C. 4.6
• D. 4.8

Answer 1

The correct option is B 4.2


Data given :
Depth of the top surface from water surface = 1.5m

Depth of the bottom surface from water surface = 6.0 m

Point of application of resultant force on flat surface is given by

$h_p={\overline{h}}_c+\frac{I_{xxC}si{n}^2\theta }{{\overline{h}}_{c}A}$

$h_p={\overline{h}}_c+\frac{I_{xxC}si{n}^2\theta }{{\overline{h}}_{c}A}$

$=3.75+\frac{b\times {4.5}^3\times si{n}^2\left(90\right)}{12\times \left(3.75\right)\times (4.5\times b)}$

$h_p=4.2m$

$h_p=$ Point of application of resultant force from water surface.

$\overline{h}=$ C.G of surface from water surface.

$\theta =$ Inclination of plane surface with horizontal.