Sorry if this is an incredibly basic question for these categories. Basically, I don't understand why I'm not getting these types of problem. I'm sure it's something really simple I'm missing.
So let's say there's an open swimming pool with width $w$, length $l$, depth $d$, and density $\rho$ (equal to water's density).
So basically, I'm quite sure the formula I should be using for this is $P = \rho gd$. This turns into $\frac{F}{A}=\rho gd$
How would I go about finding the force the of the water onto the sides ($w$ and $l$)? In a problem like this, what would the area $A$ represent? If I wanted to find the pressure on a $w$ side, would I use $w\times h$? I try this but it doesn't work. I get $F = \rho gwh^2$. But this answer is double the actual answer. It seems like I'd need to integrate (that's what I tried first) but it didn't work either.
There has to be some really basic concept I didn't understand.