00:01
Okay, so question 1a asks for the absolute pressure.
00:04
The formula for absolute pressure is this.
00:08
Atmospheric pressure plus the product of the density of the fluid, the acceleration due to gravity in the height or depth.
00:17
So that atmospheric pressure is 1 .013 times 10 raised to 5 pascal.
00:23
So the density of the fluid, in this case the fluid is ocean, so the seawater has a density of 1 ,024 kilogram per meter cube.
00:35
The acceleration due to gravity is 9 .8 meter per second squared, and we are giving the depth of 7 miles.
00:41
So that is 7 times 1 .6 kilometer.
00:45
So 1 .6 kilometer is 1 ,600 meters.
00:50
Solving, we can find that the absolute pressure is 1 .125 times 10 raised to 8 pascal.
01:03
Now, question be asked for the neb force on the porthole that is a diameter of 15 cm if the inside of the vessel is maintained at atmospheric pressure.
01:16
So since the formula for pressure is force over area, then force is equals to the product of this force, of this pressure, and the area of the porthole, where this one is just the difference of the absolute pressure in the atmospheric pressure.
01:43
So, an answer to a minus the atmospheric pressure.
01:47
Then we have, so the radius is half of the diameter.
01:59
We are given the diameter.
02:07
So we have this.
02:08
Then solving, you have 1 .125 times 10 raised to 8 pascal's minus 1 .013 times 10 raised to 5 pascal.
02:23
Note that this pressure is called gauge pressure.
02:26
So this one is gauge pressure.
02:28
This one is gauge pressure.
02:32
So 15 centimeters in meters is 0 .15.
02:43
In solving, we can find that the force is 1 .986 times 10 raised to 6 tons.
02:52
Now question 2 as for the height.
02:59
You can determine that from the formula for gauge pressure.
03:05
Which is this, and isolating the height to the left side.
03:11
We have this...