Answer: Calculate Net Force of Water on Dam of Width 'w' and Depth 'd

[forty]

Water stands at depth 'd' behind a dam of width 'w'.

i.
Find an expression for the net force of the water on the dam.

ii.
Evaluate the net force on a 100m high dam with a 60m water depth.

Attempt
For the first part:

p=F/A
A=wd
pwd=F

Then integrate from 0 to d which gives .5pw(d^2).
Does this even look remotely correct, i have a feeling there should be a g somewhere in there?

As for the 2nd part I'm stumped, how do I find the p term from that information.

Any help as always is greatly appreciated :)

 

[Doc Al]

Then integrate from 0 to d which gives .5pw(d^2).
Does this even look remotely correct, i have a feeling there should be a g somewhere in there?

How does pressure in a liquid depend upon depth?

 

[forty]

Weight of the water above it?

 

[Doc Al]

Weight of the water above it?

Give a precise formula for pressure as a function of distance below the surface. (Look it up!)

 

[forty]

P = Po + pdg

p = density

But how do i relate that to what I'm doing >.<