Pressures at the water levels in the two open tanks?

[MechaMZ]

[PLAIN]http://img814.imageshack.us/img814/3943/fluidmechanics.jpg

Please let me know is my assumption correct?

P₁ = P₂ = P₄ = P₅ = Atmospheric pressure

P₂ not equal to P₃, and P₃ is not under the atmospheric pressure.

P₂ not equal to P₃ even are the same fluid, is because of the same fluids are not connected. Am i right to say that?

# How do i convert -30mm Hg(mercury) to pressure?

 

[rl.bhat]

# How do i convert -30mm Hg(mercury) to pressure?

Pressure P = ρ*g*h, where ρ is the density of the mercury.