流體力學Fluid mechanics

On the level between x and y, consider the left tube of the manometer (i.e. the closed end one).
Pressure at this level = pressure on oil surface of tank = 35k Pa
But from the manometer tube, pressure = [12k + (900)gx] Pa
where 900 kg/m^3 is the density of oil
g is the acceleration due to gravity
Hence, 35k = 12k + (900)gx
i.e. 23 = 0.9gx
x = 23/[(0.9).(9.81)] m = 2.605 m

On the level marked by the lower horizontal line,
pressure on the left manometer tube
= [35k + (y+1.2).(900).g] Pa
Pressure on the right manometer tube
= [100k + (1.2).(13600)g] Pa
Hence, [35k + (y+1.2).(900).g] = [100k + (1.2).(13600)g]
(0.9).(9.81)y + (1.2).(9.81).(0.9) = 65 + (1.2).(13.6).(9.81)
y = 24.3 m


2014-06-23 07:34:17 補充：
Your suppl question:
All calculations are in absolute pressure.