my big test is on monday

[camuhrun]

My exam for my ow course is monday and so i'm really trying to study up. One of my review questions asks how much air will a balloon contain at the surface if it was filled with 1 cu. ft of air at 99 ft?

i am thinking 5 b/c 99 ft. is 4 atm. but idk, thats why i'm asking.

and also this one: a baloon with 1 cu ft. of air taken from the surface to 66 ft will have how much air? is it 1/3 of a quart??

thanks!

 

[knotical]

Well done, you got the numbers right and remembered to account for the 1 atmosphere at the surface. All you did "wrong" was change cubic feet to quarts in your second problem. Sounds like you'll do fine.

 

[jbd]

My exam for my ow course is monday and so i'm really trying to study up. One of my review questions asks how much air will a balloon contain at the surface if it was filled with 1 cu. ft of air at 99 ft?

i am thinking 5 b/c 99 ft. is 4 atm. but idk, thats why i'm asking.

and also this one: a baloon with 1 cu ft. of air taken from the surface to 66 ft will have how much air? is it 1/3 of a quart??

thanks!

Where did you come up with the quart :06:

 

[The Kraken]

Depends on how big the balloon is.
If it's one of those little ones, it's not going to contain any because iz gonna 'splode before it gets to the surface.

 

[pete340]

My exam for my ow course is monday and so i'm really trying to study up. One of my review questions asks how much air will a balloon contain at the surface if it was filled with 1 cu. ft of air at 99 ft?

i am thinking 5 b/c 99 ft. is 4 atm. but idk, thats why i'm asking.

4 cu. ft. It's going from 4 atm. to 1 atm. If the temperature stays constant you have P1*V1 = P2*V2. 4*1 = 1*V2, so V2 is 4.

 

[camuhrun]

Where did you come up with the quart :06:

oops...the questions says "a balloon with 1 quart of air taken from the surface to 66 ft will have how much air?"

 

[knotical]

4 cu. ft. It's going from 4 atm. to 1 atm. If the temperature stays constant you have P1*V1 = P2*V2. 4*1 = 1*V2, so V2 is 4.

pete340 is correct.

 

[cmalinowski]

33' = 2x
66' = 3x
99' = 4x

(depth/33)+1

Don't worry, you'll do fine. Just try and visualize it.

What got me was that it was not exponetial: if it's 1/2 at 33', why is it not 1/4 at 66'? While I understand it, I thought about this during my course at the beginning...

 

[Xman]

Dive physics in imperial measurements just sucks. Metres and litres is just so much simpler (as are most computations in metric).
As far as the answers go, you were right (as others have stated) about 99ft being 4atm. As pete340 pointed out, your mistake was calculating as though you were going back to 0 atm, when in fact the surface is 1atm.
Seems like you understand the overall concept and just made a mistake. Try a few more problems to be sure you've got it, but you should be fine.

 

[pete340]

As pete340 pointed out, your mistake was calculating as though you were going back to 0 atm, when in fact the surface is 1atm.

No, at 0 atm. Kraken's answer is right: the balloon would explode long before it reached infinite volume.