Engineering maths problem?

Question

A vertical retaining wall contains water to a depth of 15 meters. calculate the center pressure and the turning moment about the bottom for a unit width. take the density as 1000 kg/m^3.

Any Ideas anyone?

Answer 1

The centre of pressure is found with

yp=s+b/2+b^2/(12(s+b/2))

where yp=distance to centre of pressure from top

s=distance from surface to top of object

b=height of object

yp=0+15/2+15^2/(12(15/2))=10 m

(You'll notice its always 2/3 of the depth for a wall that touches the surface and the bottom)

The centre of pressure is then 10 m from surface or 5 m from the bottom.

To calculate moment you need force so

Force=Pressure*Area=Density*Height*Gra...

F=1000 kg/m^3 * 15m^2 * 9.81 m/s^2 * 5m

F=735750 N*m or 735.75 kN*m

Answer 2

I just know it is 1 bar pressure for every meter of water.