In: Physics
The deepest point known in any of earth's oceans is in the Marianas Tench, 10.92 km deep.
a) Assuming water is incompressible, what is the pressure at this depth? Use the density of seawater.
b) The actual pressure is 1.16 X 108 Pa your calculation will be less because the density actually varies with depth. Using the compressibility of water and the actualpressure, find the density of the water at the bottom of the Marianas Trench. What is the percent change in the density of the water?
The answer to a is 1.0712 x 10^8 Pa.
What is b?
(1) We know that
pressure= pgh
where p is the density , g is the acceleration due to gravity and h is the height or depth
Pressure (P) = 1025*9.81*10.92*103 = 1.098*108 Pa
(2) We know that
compressibility = volumetric strain /Pressure = (dV/V) /P
dV = VS - VD
where VS is the volume at surface and VD is the volume at depth
Compressiblity = (VS - VD) /VS*P = (1-VD/VS) /P
(1-VD/VS) = Compressibility*Pressure
(1-ps /pD) = 45.8*10-11*(1.16*108 Pa)
ps = 1025 kg/m3
pD = 1082.511 kg/m3
(3)
percentage change in the density = (pD - ps / ps )*100 = ((1082.511 - 1025) / 1025)*100 = 5.61%