Register to reply

Pressure liquid

by batballbat
Tags: liquid, pressure
Share this thread:
batballbat
#1
Nov26-11, 08:36 AM
P: 127
what would the pressure of liquid at a depth be in a container which is slanted?
Phys.Org News Partner Physics news on Phys.org
Physicists discuss quantum pigeonhole principle
First in-situ images of void collapse in explosives
The first supercomputer simulations of 'spin?orbit' forces between neutrons and protons in an atomic nucleus
batballbat
#2
Nov26-11, 08:41 AM
P: 127
i suspect [tex] h.d.g.sinAngle [/tex]. correct me if i am wrong
russ_watters
#3
Nov26-11, 10:04 AM
Mentor
P: 22,237
No, the shape of the container is irrelevant.

http://en.m.wikipedia.org/wiki/Fluid_statics

batballbat
#4
Nov26-11, 10:11 AM
P: 127
Pressure liquid

in the derivation of the pressure of liquid, the weight is assumed to act perpendicular to the column of liquid. Plz comment
russ_watters
#5
Nov26-11, 01:24 PM
Mentor
P: 22,237
Gravity pulls straight down, so...
batballbat
#6
Nov26-11, 08:54 PM
P: 127
of course but i find similar case to the inclined plane. can somebody give a reasoning?
russ_watters
#7
Nov27-11, 01:36 AM
Mentor
P: 22,237
What do you find similar about an inclined plane? What is YOUR reasoning?
batballbat
#8
Nov29-11, 11:05 PM
P: 127
somebody reply
Doc Al
#9
Nov30-11, 04:33 AM
Mentor
Doc Al's Avatar
P: 41,306
The pressure depends on the depth beneath the surface, which is not slanted. As already stated, the shape of the container--whether slanted or vertical--is irrelevant.

If you want more, give a specific example of what you have in mind with a diagram.
russ_watters
#10
Nov30-11, 06:44 AM
Mentor
P: 22,237
Sorry, we don't spoonfeed here. If you want to learn/want help, you need to show some effort at trying to figure it out for yourself. Then when you make a wrong turn, we'll nudge you back in the right direction.
batballbat
#11
Nov30-11, 07:25 AM
P: 127
wouldnt this imply that the liquid would accelerate at g in slanted tubes?
Doc Al
#12
Nov30-11, 07:54 AM
Mentor
Doc Al's Avatar
P: 41,306
Quote Quote by batballbat View Post
wouldnt this imply that the liquid would accelerate at g in slanted tubes?
No. Please describe exactly what you have in mind. Are you talking about hydrostatic pressure? (Which is what I assumed.) Or fluid dynamics?
russ_watters
#13
Nov30-11, 11:40 AM
Mentor
P: 22,237
g is acceleration due to gravity. If you block that acceleration, the required force is f=mg. Aka, weight.
DaveC426913
#14
Nov30-11, 11:50 AM
DaveC426913's Avatar
P: 15,319
Quote Quote by batballbat View Post
wouldnt this imply that the liquid would accelerate at g in slanted tubes?
Since you're talking about pressure-at-depth then you're talking about a container full of fluid (as opposed to, say, an air-filled container with an amount of water placed in it).

Water suspended in water is neutrally buoyant, so its not like some arbitrary mass of water is going to start sliding to the bottom, accelerating under gravity.
batballbat
#15
Nov30-11, 11:55 PM
P: 127
No. Please describe exactly what you have in mind. Are you talking about hydrostatic pressure? (Which is what I assumed.) Or fluid dynamics?

I am not familiar with the terms but i guess you are asking whether i am talking about stationary fluids or flowing ones. Eg. in an inclined plane, there is a mass a top, even though its weight acts exactly downward, it would rather move along the plane. And the force with with it moves along the plane is lesser according to its slope. Same for liquids. But as dave said while the liquid is continuous and stationary, the force with with a finite upper part of liquid exerts on the lower part will be the same as for the case of liquids in vertical column. This is not clear to me.

Eg. lets take a column of liquid standing upright and pour some water into it. And then slant it a bit. Then the depth of the liquid increases even though it is not continuous on the upper part (i hope this is understood). So as the depth increases although not uniformly, the pressure in one side must increase. Help me out with this.
D H
#16
Dec1-11, 02:51 AM
Mentor
P: 15,065
Pascal's vases:




Another set:




Notice that no matter how weird the shape, the tops of the liquid surfaces in the different containers are at the same level. The pressure difference in some container from bottom to top does not depend on shape. It depends only the height of the liquid.
batballbat
#17
Dec1-11, 05:21 AM
P: 127
i havent learned any of hydrodynamics or hydrostatics. So i think this phenomenon is taken as as true. Is there a proof for it?
D H
#18
Dec1-11, 05:25 AM
Mentor
P: 15,065
The diagram and image (real) I posted in post #16 are pretty solid evidence. Hydraulic pumps rely on this principle.


Register to reply

Related Discussions
Why liquid boils when the envrionmental pressure equals its saturated vapor pressure General Physics 4
Pascal's Law - pressure inside the liquid vs. force needed to lift the liquid Introductory Physics Homework 1
Liquid pressure Classical Physics 2
Liquid pressure General Physics 1
Vapor pressure vs liquid pressure in enthalpic combustion reaction Biology, Chemistry & Other Homework 0