Need help with Physics question :)

Modtrocity · Post by **Modtrocity** » Thu Aug 30, 2007 4:02 pm

I got a question on my physics homework that I can't figure out. (Darn college physics! >.<)

I don't know if anyone here is good with physics... but here it goes:

Using Archimedes' Principle, estimate the mass that can be lifted by
a balloon measuring 30 feet in diameter. The temperature of the air
in the balloon is 70 degrees Celcius and its pressure is 1 atm (atmosphere).

Archimedes' principle - The total mass of a floating object equals the mass of the fluid displaced by the object.

All help with this problem is appreciated!

G.I.R. · Post by **G.I.R.** » Thu Aug 30, 2007 4:05 pm

in b4 not ur personal tutor

Modtrocity · Post by **Modtrocity** » Thu Aug 30, 2007 4:08 pm

G.I.R. wrote:in b4 not ur personal tutor

Huh?

G.I.R. · Post by **G.I.R.** » Thu Aug 30, 2007 4:10 pm

Halomods isn't your personal tutor.

CptnNsan0 · Post by **CptnNsan0** » Thu Aug 30, 2007 4:11 pm

don't comment if your not gunna help

.

G.I.R. · Post by **G.I.R.** » Thu Aug 30, 2007 4:13 pm

[hypocrite]

CptnNsan0 wrote:don't comment if your not gunna help .

[/hypocrite]

Seriously, Halomods isn't the place to be asking for help with your homework.

Modtrocity · Post by **Modtrocity** » Thu Aug 30, 2007 4:14 pm

I not forcing you to help me. I'm just stuck on this question and was wonding if anyone knew how to solve it.

G.I.R. wrote:[hypocrite]
CptnNsan0 wrote:don't comment if your not gunna help .
[/hypocrite]

Seriously, Halomods isn't the place to be asking for help with your homework.

Yet we talk about youtube, myspace, what makes us happy, UFOs, rants, cars, paintballing, and money...

If a mod doesn't want this here, let them worry about it.

newbymodder · Post by **newbymodder** » Thu Aug 30, 2007 4:28 pm

no joke i ask on forums when i get stuck on crap and i don't recall any where stating you can't post questions like this? if so show me where in the rules and i'll shut up.....

as for the question im sry i can't help i suck at physics as well

Prey · Post by **Prey** » Thu Aug 30, 2007 4:37 pm

Up to one less than the weight of the fluid displaced by the object. You can do the math yourself >_>

Modtrocity · Post by **Modtrocity** » Thu Aug 30, 2007 4:37 pm

Hi newby. :p

Darn physics.

Prey wrote:Up to one less than the weight of the fluid displaced by the object. You can do the math yourself >_>

I still don't understand. Sorry.

newbymodder · Post by **newbymodder** » Thu Aug 30, 2007 4:58 pm

Using Archimedes' Principle, estimate the mass that can be lifted by
a balloon measuring 30 feet in diameter. The temperature of the air
in the balloon is 70 degrees Celcius and its pressure is 1 atm (atmosphere).

Archimedes' principle - The total mass of a floating object equals the mass of the fluid displaced by the object.

Prey wrote:Up to one less than the weight of the fluid displaced by the object. You can do the math yourself >_>

trying to clear it up by underlining what goes together lol although i probably could figure it out it just takes me along time hope this helped modtrocity

Andrew_b · Post by **Andrew_b** » Thu Aug 30, 2007 5:04 pm

Modtrocity wrote:paintballing

Lol...that was also for school...so we both have posted hw questions on halomods...

yeah i needed a pb gun for school believe it or not.

Dissolution241 · Post by **Dissolution241** » Thu Aug 30, 2007 5:11 pm

I doubt you'll get much help here. Try Yahoo! Answers. If you don't have a Yahoo ID, make one, doesn't take long and ask your question in the Mathematics section.

Iron_Forge · Post by **Iron_Forge** » Thu Aug 30, 2007 7:13 pm

http://en.wikipedia.org/wiki/Archimedes%27_Principle

"The Archimedes' Principle states that when a solid body is partially or completely immersed in water the apparent loss in weight will be equal to the weight of the displaced liquid."

For starters, calculating the volume of the balloon, assuming it's a perfect sphere, is (pi*d^3)/6, or ~14,137 cubic ft. (assuming my math is correct).

However, your question is missing alot of information. You would need to know the fluid the balloon is being submersed in, and it's weight...The balloon would be able to lift the weight of 14,137 cubic feet of that fluid...

Suppose a rock's weight is measured as 10 newtons when suspended by a string in a vacuum. Suppose that when the rock is lowered by the string into water, it displaces water of weight 3 newtons. The force it then exerts on the string from which it hangs will be 10 newtons minus the 3 newtons of buoyant force: 10 − 3 = 7 newtons.

So to answer your question, I'm old, it's been along time since I took physics, there's alot of math I completely ignored relative to your question, I drink alot, and I don't know the answer to your question...Except that rocks are way heavier than balloons...Except balloons filled with rocks...

Modtrocity · Post by **Modtrocity** » Thu Aug 30, 2007 7:23 pm

Iron_Forge wrote:http://en.wikipedia.org/wiki/Archimedes%27_Principle

"The Archimedes' Principle states that when a solid body is partially or completely immersed in water the apparent loss in weight will be equal to the weight of the displaced liquid."
For starters, calculating the volume of the balloon, assuming it's a perfect sphere, is (pi*d^3)/6, or ~14,137 cubic ft. (assuming my math is correct).

However, your question is missing alot of information. You would need to know the fluid the balloon is being submersed in, and it's weight...The balloon would be able to lift the weight of 14,137 cubic feet of that fluid...

Suppose a rock's weight is measured as 10 newtons when suspended by a string in a vacuum. Suppose that when the rock is lowered by the string into water, it displaces water of weight 3 newtons. The force it then exerts on the string from which it hangs will be 10 newtons minus the 3 newtons of buoyant force: 10 − 3 = 7 newtons.
So to answer your question, I'm old, it's been along time since I took physics, there's alot of math I completely ignored relative to your question, I drink alot, and I don't know the answer to your question...Except that rocks are way heavier than balloons...Except balloons filled with rocks...

Hmm. The balloon actually isn't in water. I need to find how much weight it can carry when flying in the air. (Hot air ballon). Seeing how hard this is, no wonder my teacher gave us 2 weeks to do this homework...

newbymodder · Post by **newbymodder** » Thu Aug 30, 2007 8:03 pm

Iron_Forge wrote:So to answer your question, I'm old, it's been along time since I took physics, there's alot of math I completely ignored relative to your question, I drink alot, and I don't know the answer to your question...Except that rocks are way heavier than balloons...Except balloons filled with rocks...

omg Iron Forge u have made my day for the next month lol thats basically me but by my understandings im younger than you

noxiousraccoon · Post by **noxiousraccoon** » Thu Aug 30, 2007 8:13 pm

Do you have any equations that you could post? I might be able to help if I had a few resources in front of me.

HPDarkness · Post by **HPDarkness** » Thu Aug 30, 2007 8:16 pm

I took Physics last year. I'll see if I can find my papers.

Prey · Post by **Prey** » Fri Aug 31, 2007 3:15 pm

Hmm, I retract my first statement..and blame it on my tiredness at the time ;x

Iron_Forge wrote:http://en.wikipedia.org/wiki/Archimedes%27_Principle

"The Archimedes' Principle states that when a solid body is partially or completely immersed in water the apparent loss in weight will be equal to the weight of the displaced liquid."
For starters, calculating the volume of the balloon, assuming it's a perfect sphere, is (pi*d^3)/6, or ~14,137 cubic ft. (assuming my math is correct).

It is.

Iron_Forge wrote:However, your question is missing alot of information. You would need to know the fluid the balloon is being submersed in,

We do, the fluid is the air.

Iron_Forge wrote:and it's weight...

That weight can actually be calculated from what has been given.

Iron_Forge wrote:The balloon would be able to lift the weight of 14,137 cubic feet of that fluid...

Yep pretty much.

I can't really be bothered to go into it all, but I sourced you two sites that should help out a lot:
http://www.sciencebyjones.com/hot_air_balloon.htm
http://jeffperado.blogspot.com/2006/04/ ... lloon.html

-Prey

Modtrocity · Post by **Modtrocity** » Fri Aug 31, 2007 7:28 pm

Thanks Prey, that helps.