Question

The greatest ocean depths on earth are found in the Marianas Trench near the Philippines, where the depth of the bottom of the trench is about 11.0 km. Calculate the pressure(atm)due to the ocean at a depth of 10.1 km, assuming sea water density is constant all the way down. (The validity of the assumption of constant density is examined in one of the integrated concept problems.)

Answer 1

well you have to make some assumption about what that density is.
Fresh water is about1000 kg/m^3
so its weight is about 9.81 * 10^3 Newtons/m^3
but salt water is about 1027 kg/m^3
so 10074 N/m^3
so at the bottom the pressure is
10.1 * 10^3 * 10074 = 10.2*10^7 N/m^2 or Pascals
an atmosphere is 1.013*10^5 Pascals
so we have
(10.2/1.013)* 10^2 = 10.1*10^2 = 1010 atmospheres (plus 1 atm for the air on top.)