I know this is off topic , but i need help with a problem in physics ( its one of those rare once that i dont get )

it based on hydrostatics.

In a u tube, of constant and given radius ( r ) , a liquid of a given density is added such that length ( l ) of the tube is still un occupied by the liquid on both ends.
Now, one of the ends of the tube is sealed.

What is the maximum mass of the same liquid that can be added so that the tube doesnot over flows

( take into consideration the pressure applied by the air trapped in the other end. ).

NEED IT ASAP

42

I can get you started, but I'm here at the horse barn grooming horses and cleaning stalls. See if this helps.

It's a Force problem, and governing equations are based on equlibrium of force. At the point of equilibrium and limit, you have M mass of liquid such that the tube is full on the open side, and the added liquid has compressed the sealed air volume on the other end. The key in this problem is that the line of liquid moves up as the air is compressed.

Force of the liquid pushing upwards on the air bubble = Force of the compressed air pushing down

Left side is dependent on the resulting delta in liquid height at the equilibrium point. Force pushing up can be expressed in that height difference using a new variable (say, L2) which is the height that the liquid moves upward to compress the air. Using that new variable, express in terms of M mass added, which you need to translate into units of length l using density and radius. Thinking a bit on this, this is the tough part.

Right side requires a compressibility factor for air. Does the question give you that force expression in terms of the height movement?

Once you have both sides, solve for L2, and you will get M mass.

Sorry for the rambling description but I'm on my smartphone

Manfred

Edit: Actually, you don't need compressibility or spring force.
Force of the liquid pushing upward on the air bubble due to difference in height + force of sea level air pressure = force of air pushing down on liquid after being compressed more than sea level density

HUH

I think you need to apply Boyles Law to the trapped air

Heff006 wrote: 42

Heff,

If nobody else gets it, I did. Love me Douglas Adams.

HUH

Heff006 wrote: 42

i know what u did.

42 is literally the answer to everything in this universe.

IT SOUNDS WIERD BUT ITS A FACT

42.
Could you repeat the question in the middle.

why ?

I'm with Davy " HUH "

Why

it seems only a few has read or watched The Hitchhiker's Guide to the Galaxy

and of course, you can ask google:
www.google.com/search?q=the+answer+to+li...10&es_sm=93&ie=UTF-8

I bet they don't carry a towel everywhere they go either!