Replies to this message

: water psi angle bottom
: water psi angle bottom -- charter504	Post Reply	Top of thread	Forum

Posted by: whang ® 10/22/2008, 09:10:42 Author Profile eMail author Edit

To calculate the pressure of the liquid in the container, the shape of the container does not matter how it looks like. It depends on three factors: 1) The density of the liquid 2) Gravity 3) Any height between the surface of the liquid to the bottom of the container I use the pressure formula to explain the situation as the above. Area of the bottom of the container = A Any area where the height of liquid you choose Density = D Height of the container = H Any height of the liquid you choose Volume = V= A* H Mass of the liquid = M= D * V=D* A* H Weight of the liquid =(Wt) = M * Gravity = D * A * H * Gravity Pressure (PSI) = Wt /A= M * Gravity/A = D * A * H * Gravity/A= D * H * Gravity The A of the numerator and the A of the denominator of the formula can be cancelled each other. That is the reason why the areas of the shape do not matter at all. The formula comes to: Pressure (PSI) = D * H * Gravity The pressure depends on the Height (H) of the liquid, Density (D) of the liquid and Gravity. For the above formula, I have a question for you: A crab hides in a hole at the bottom of the sea, from the sea level to the shell of the crab is 100 ft. What is the seawater pressure and what is the weight of the seawater on the shell of the crab? Assume the area of the shell of the crab is 15 sq. inch. If you can answer this question, I think you will understand how the liquid pressure works. I will give you the answer next time. Hope you will enjoy the question.

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

: water psi angle bottom
: water psi angle bottom -- charter504	Post Reply	Top of thread	Forum

Posted by: jboggs ® 10/21/2008, 15:59:20 Author Profile eMail author Edit

The top of the angled section is a certain distance from the top of the water. The bottom of the angled section is a greater distance from the top of the water. The pressure at any point is based on its distance from the top of the water. So, that means that the pressure the angled section will see will vary from its top to its bottom, based on their respective distances from the top of the water. The pressure is not constant over the length of the angled section.

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

| |

: water psi angle bottom
: water psi angle bottom -- charter504	Post Reply	Top of thread	Forum

Posted by: randykimball ® 10/20/2008, 15:46:16 Author Profile eMail author Edit

Welcome... The shape of the sides near the bottom (or anywhere else) of a chamber have no effect on the PSI due to the depth of the fluid. This seems wrong to quite a few people but shape does not matter, a square inch of bottom is still a square inch of bottom and the depth is still the depth. For example: If I have a chamber that is 1 foot by 1 foot at the bottom and it is 6 feet deep it is a given PSI based on the 6 foot depth per the weight of that fluid per foot of depth. ... If I have a chamber with a 1 inch x 1 inch top filler area, it is tappered out to 3 feet by 6 feet in the middle and ends up tappered back in to 3 inches by .5 inches at the bottom, and is also 6 feet deep, ... the PSI at the bottom is still 6 feet times the weight of that fluid per foot of depth. In both conditions PSI is still Pounds Per Square Inch. The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them. Modified by randykimball at Mon, Oct 20, 2008, 15:48:07

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

| |

: water psi angle bottom
: water psi angle bottom -- charter504	Post Reply	Top of thread	Forum

Posted by: devitg ® 10/19/2008, 17:46:26 Author Profile eMail author Edit

Pressure at any given point is as Specific weight times deep , in consistent units So take the measure from the hole to the free water surface. So the pressure increase from the upper 45°side to the bottom 45°.

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

| |

: : water psi angle bottom
: : water psi angle bottom -- devitg	Post Reply	Top of thread	Forum

Posted by: charter504 ® 10/20/2008, 16:53:55 Author Profile eMail author Edit

if i had a rectangle tank that was 26 inches high by 8 by 8, and i had a 1 square inch corner bottom with 2 slants at 55 degrees coming up to 11 inches high on the walls, what is my water pressure in the 1 inch square corner?

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

| |

: : : water psi angle bottom
: : : water psi angle bottom -- charter504	Post Reply	Top of thread	Forum

Posted by: jboggs ® 10/20/2008, 17:24:54 Author Profile eMail author Edit

A good way to understand this is to realize that unlike force (which has a direction) pressure is "omni-directional". It is the same in all direcitons. A molecule of water at 25 psi is exerting that pressure in ALL directions, not just against the surface that is supporting it. So, whether that limiting surface is underneath that molecule, or by its side, or even on top of the molecule, it still feels the same pressure. This means that a molecule that is touching both the bottom and the side of a tank is exerting the same pressure against both. The only thing that will cause the pressure of that molecule to vary from its neighbors is its distance from the top surface of the liquid.

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

: : : water psi angle bottom
: : : water psi angle bottom -- charter504	Post Reply	Top of thread	Forum

Posted by: randykimball ® 10/20/2008, 17:07:44 Author Profile eMail author Edit

Please, we understand what you are thinking. MANY people have a hard time grasping this concept, you are quite normal. It just seems to most people that curved, or tapered shapes, or the fact that water is not actually over the spot will effect the PSI, but it does not. Carefully read the following examples meant to help you understand. Example one: (your case study) Water weighs 62.3 pounds per cubic foot. This means it weighs 62.3/144 (= .4326 pounds) per 1 inch square by 1 foot tall. This means 26 inches of water by 1 square inch above a 1 square inch at the bottom has a PSI of .4326 x(26/12)= .9373 pounds, no matter where you measure it as long as it is 26" below the top water level at around 70 degrees F. Those slants do NOT matter. Example two: If you have a water tower in your city it is there to provide water pressure (PSI) to all houses below. How much water pressure each house has is dependant on how far their house is below the top of the water in the tower. However, as the water flows this pressure is then effected by the size of the pipes, kinds of turns, and distance from the tower because of flow dynamics. BUT, with no water running a guage will read PSI accordingly to the level they are from the top of the water level in that tank.. period. ... although there is no water over your actual house. Example three: If you have water in a plastic PVC pipe with a hundred turns, wierd runs, bends, joints, goes around your car ten times and ends at a pressure gauge 26 inches below the top of the water level .... the gauge will read the same .9373 PSI. Example four: It does not matter if it is a tank with a million gallons or a piece of pipe 26" tall, at a depth of 26" the PSI is going to be the same. The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them. Modified by randykimball at Mon, Oct 20, 2008, 17:43:44

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

| |

: : : : water psi angle bottom
: : : : water psi angle bottom -- randykimball	Post Reply	Top of thread	Forum

Posted by: charter504 ® 10/20/2008, 17:41:31 Author Profile eMail author Edit

so you are saying ther is in this pressure system a column of 1 square inch that goes up 26 inches to the top. Are you saying that the rest of this water is not trying to escape the container at all? That is doesn't weigh in towards the column with its weight and therefore increase the pressure?

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

| |

: : : : : water psi angle bottom
: : : : : water psi angle bottom -- charter504	Post Reply	Top of thread	Forum

Posted by: randykimball ® 10/20/2008, 17:45:40 Author Profile eMail author Edit

yep... but, it IS trying to escape in every dirrection at a strength according to its depth. BUT... realize the minute you start moving that water everything changes... OK? The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them. Modified by randykimball at Mon, Oct 20, 2008, 17:47:54

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

| |

: : : : : : water psi angle bottom
: : : : : : water psi angle bottom -- randykimball	Post Reply	Top of thread	Forum

Posted by: randykimball ® 10/21/2008, 09:04:18 Author Profile eMail author Edit

charter, Please let us know if our answers helped you to understand. This kind of feed back helps us to improve our abilities to explain concepts to other humans. It is often not easy for engineering mind types to express concepts to others and we have to make a effort to learn and improve this skill. The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them.

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

| |

: : : : : : : water psi angle bottom
: : : : : : : water psi angle bottom -- randykimball	Post Reply	Top of thread	Forum

Posted by: charter504 ® 10/21/2008, 14:23:00 Author Profile eMail author Edit

I just dont see how a tank wouldn't excert more of its weight on the lowest point. You might be telling me that gravity wont add weight down an angle like a playground slide.

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

| |

: : : : : : : : water psi angle bottom
: : : : : : : : water psi angle bottom -- charter504	Post Reply	Top of thread	Forum

Posted by: randykimball ® 10/21/2008, 14:38:01 Author Profile eMail author Edit

I understand your difficulty to grasp this, you are perfectly normal. Think about this gadget. If you put a 1/4" plastic tube onto a fitting at the bottom of a 5 gallon bucket, and run that fitting through your house to a distant room and then tape it up in a corner so the water won't run out. Then you fill the bucket with water exactly 12 inches deep off the floor. Now you go into the other room where you drug the tube and measure up off the floor to the water line. You will know if your distant corner is level with the bucket spot on the floor. NOW.... the bucket is several inches in diameter, right? The tube is about 3/16 inside diameter, right? Why doesn't the water run up the tube? Because the pressure in the opening of the tube is the same on both ends.... 12 inches of water head. So, if you want to you can consider this law of physics of fluids as a law of head height. If you have a cube 12 inches square full of ambent air and sink it in the ocean to a depth of 1 mile, it is the depth that figures into the head height for PSI not the volume of the ocean. Does that help? ... any? The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them. Modified by randykimball at Tue, Oct 21, 2008, 14:40:31

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread