Science Question - Argument with wife.

@rosborne979,

Quote:

Are you asking about Buoyancy, or Weight, or Mass?

That depends Ros.
Can i salvage a tecnical victory with one of them?

2 Replies

@dadpad,

No, but it might impress her if you mastered all those terms in defeat.

1 Reply

@engineer,

engineer wrote:

No, but it might impress her if you mastered all those terms in defeat.

I doubt that.
Currently she exploring the question would an empty jar weigh more than one with my penis in it.

0 Replies

What's the weight difference?

If a jar of air weights exactly one pound and you pull a vacuum on the contents, what is the new weight of the jar.

I need data.
Joe (Not circumspection)Nation

0 Replies

@dadpad,

dadpad wrote:

My wife is convinced that a jar full of vaccume weighs less than a jar full of air.
Assume an air tight cover that will hold an absolute vaccume.

My theory is that the air presure outside the jar continues to press down at a consistent pressure regardless of what pressure is inside the jar and that the jar will weigh the same with or without vaccume.
Am I right?

African or European jar?

1 Reply

@Ticomaya,

Ticomaya wrote:

African or European jar?

Velocity doesnt come into it Tico.

what?

0 Replies

@dadpad,

Mompad is right. I'm gonna get a hot air balloon and fill it with vacumn. We going to go up like a rocket.

1 Reply

@roger,

Quote:

Concept Title: Vacuum-based lighter-than-air craft
Description: This concept is for a very large lighter-than-air platform that uses a partial vacuum to generate lift rather than a low density gas (e.g., hydrogen, helium). The key feature of such a craft is the need for it to be very large.

http://csat.au.af.mil/2025/concepts/900897.HTM

1 Reply

Is all this is true why not mak cars with vacuum spaces in the side panels and roof.
They would be lighter and cost less fuel to run.

2 Replies

@dadpad,

I often feel quite light-headed which gives one pause for thought whether or not a vacuum has anything to do with it.

In those empty moments I pause in wonderment not remembering what I've forgotten but with the contented feeling that a great weight has been lifted from my shoulders.

1 Reply

@tsarstepan,

Great stuff, but I just tried it. My balloon is flatter than a fritter. What went wrong?

1 Reply

@laughoutlood,

Quote:

I often feel quite light-headed which gives one pause for thought whether or not a vacuum has anything to do with it.

Does the vacuume give you an edge orally, so to speak?.

0 Replies

@dadpad,

dadpad wrote:

Is all this is true why not mak cars with vacuum spaces in the side panels and roof.
They would be lighter and cost less fuel to run.

A panel with a vacuum chamber would weigh more than one with air inside because it would need to be made strong enough to resist the pressure of the atmosphere which would try to flatten it, and in any case the weight of such a small volume of air would be quite small. Air weighs 1.2 kg per cubic metre at sea level. The whole of a typical car's interior is around 5 cubic metres so all the air in a car's inside would weigh around 6 kg. Just the air in the panels would be a negligible weight, and the panels would be heavier thus cancelling out (and more) any energy savings.

The trouble with "vacuum balloons" is that a strong enough vessel would need to be so heavy that the buoyancy afforded by the vacuum would be more than cancelled.

0 Replies

@roger,

roger wrote:

Great stuff, but I just tried it. My balloon is flatter than a fritter. What went wrong?

Did u cram enuf vacuum into it ?

0 Replies

what about...
if the jar was in another dimension?

1 Reply

Some simple number stuff. A spherical vessel with an internal volume of 1 cubic metre would be 1.24 metres across (about 4 feet). At sea level, If you had 2 such vessels, one filled with air at the local atmospheric pressure, and one with a vacuum, the one with air in would weigh 1.2 kg (around 2lb 11 oz) more. However, the surface area of the vessel would be 12.5 square metres and the atmosphere would press on it with a force of 132 metric tonnes (about 146 short tons). Thus the vessel would have to be very stoutly made and would be quite heavy. (Many tons)

http://www.lesker.com/newweb/chambers/jpg/photo/Photo-CH-18inSphere_Chamber.jpg

1 Reply

@dadpad,

dadpad wrote:

what about...
if the jar was in another dimension?

One with heavy vacuums ?

0 Replies

@contrex,

OmSigDAVID wrote:

dadpad wrote:
what about...
if the jar was in another dimension?
One with heavy vacuums ?

and aliens... who abduct the jar.

contrex wrote:

Some simple number stuff. A spherical vessel with an internal volume of 1 cubic metre would be 1.24 metres across (about 4 feet). At sea level, If you had 2 such vessels, one filled with air at the local atmospheric pressure, and one with a vacuum, the one with air in would weigh 1.2 kg (around 2lb 11 oz) more. However, the surface area of the vessel would be 12.5 square metres and the atmosphere would press on it with a force of 132 metric tonnes (about 146 short tons). Thus the vessel would have to be very stoutly made and would be quite heavy. (Many tons)

Now... thats just silly contrex. Your vessel bears no resemblance to a jar. and you have two of them. how are you gonna carry them down to the beach.

1 Reply

DP wrote:

how are you gonna carry them down to the beach.

Sheesh! Quite simple:
- Get a reversible pump, a balloon and a helium tank.
- Attach the balloon to the jar, fill the balloon with helium, go to the beach pulling the balloon with a string.
- When you arrive at the beach, connect the pump in reverse to the jar, make the vacuum..

That's it! Twisted Evil

1 Reply

@dadpad,

dadpad wrote:

OmSigDAVID wrote:

dadpad wrote:
what about...
if the jar was in another dimension?
One with heavy vacuums ?

and aliens... who abduct the jar.

Have u consulted the I.N.S. ?

0 Replies

Science Question - Argument with wife.

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