proton boron 11 fusion / fission shielding

KitemanSA · Post by **KitemanSA** » Wed Mar 11, 2009 1:52 pm

chrismb wrote:Which is heavier - an ounce of feathers or an ounce of gold? ...
which is heavier - a pound of feathers or a pound of gold?

I know; so I'll let others Troy for an answer.

MSimon · Post by **MSimon** » Wed Mar 11, 2009 1:54 pm

chrismb wrote:Which is heavier - an ounce of feathers or an ounce of gold?

If you think you know that one, try;
which is heavier - a pound of feathers or a pound of gold?

Depends on how you measure.

lbf or lbm.

If you compare them on a scale not in a vacuum the feathers have more mass - due to buoyancy.

blaisepascal · Post by **blaisepascal** » Wed Mar 11, 2009 4:09 pm

chrismb wrote:Which is heavier - an ounce of feathers or an ounce of gold?

If you think you know that one, try;
which is heavier - a pound of feathers or a pound of gold?

Aww, that's easy... An ounce of gold is 480 grains, while an ounce of feathers is 437.5 grains, so the gold is heavier. A pound of gold is 5760 grains, while a pound of feathers is 7000 grains, so the feathers are heavier.

olivier · Post by **olivier** » Wed Mar 11, 2009 5:47 pm

The avoirdupois system is too sophisticated for my metric mind. Must have been a merchant's trick to cheat honest travellers from the continent.

One advantage of not being a native English speaker is that I feel allowed to ask a basic question without shame :
What does the word "heavy" mean?
In a sense, Msimon is on the right track: same mass, different interaction with a weighing device.
Changing perspective: the quantity of matter being kept unchanged, the mass will increase with the temperature. Starting from thermal equilibrium, gold, being a better temperature conductor, will get heavier than feathers if you heat the whole system (and vice versa).

chrismb · Post by **chrismb** » Wed Mar 11, 2009 6:52 pm

blaisepascal wrote:
Aww, that's easy....

...with wikipedia!!

Are feathers lighter when they are flying?

If you have a truck full of homing pigeons on their perches and you bang the box so they all take off, inside the truck, does the truck get lighter?

Skipjack · Post by **Skipjack** » Wed Mar 11, 2009 7:00 pm

No, it does not.

D Tibbets · Post by **D Tibbets** » Wed Mar 11, 2009 7:35 pm

Err... that depends. If the birds are flying in a closed box, then the weight would not change, if they are in an open cage so that some of the displaced air can flow in a general downward direction outside of the truck at a rate faster than replacement air flows in from the upward direction then the weight would be decreased (measured weight if the scale is kept under the truck)- upward thrust. Or, if the birds are flapping/ pumping air outside the cage/ truck fast enough to create a partial vacuum then the system would measure a lower weight- lift or bouyancy....I think.

Which would weigh more in Brazil, a truck traveling East or West?

Dan Tibbets

KitemanSA · Post by **KitemanSA** » Wed Mar 11, 2009 7:37 pm

Skipjack wrote:No, it does not.

HMMM, deeply theoretical discussion!

Skipjack · Post by **Skipjack** » Wed Mar 11, 2009 8:51 pm

Nope not theoretical anymore. Mythbusters actually tried it in an episode. Of course you might make a totally open truck where the air can flow outside and what not. That would not count as "in" a truck though would it?

MSimon · Post by **MSimon** » Thu Mar 12, 2009 3:41 am

Which would weigh more in Brazil, a truck traveling East or West?

Describe the size and shape of the bikini.

Roger · Post by **Roger** » Mon Mar 16, 2009 4:02 pm

MSimon wrote:
Which would weigh more in Brazil, a truck traveling East or West?
Describe the size and shape of the bikini.

Is it a thong, or a 3/4 ?

tombo · Post by **tombo** » Mon Mar 16, 2009 7:08 pm

(Wikipedia tells the story differently, but I'm sticking by my Dad!)

I live in lumber country and have dealt with lumbermen so I buy your dad's version.
I live in 100+ year old house with old-growth real 2x4's that just about take a metal blade to cut into.
The combination makes renovations interesting.

D Tibbets · Post by **D Tibbets** » Mon Mar 16, 2009 10:52 pm

MSimon wrote:Describe the size and shape of the bikini.

I suppose it would depend on weather it was festival time in Rio.. in which case my highway speed would be higer in that direction! But, what I was actually fishing for was orbital dynamics and the difference between mass and weight. Driving East (maximized effect at the equater) adds to the speed you already have from the Earth's rotation, centrifical (?) force is making you weigh less. That's why less additional speed is needed to reach an equatorial orbit, compared to a polar orbit.

Dan Tibbets