Kilogram of steel v’s a kilogram of feathers
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6
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I’m really really sorry about this but i’m Having a discussion at the moment regarding a mass of one kilogram of feathers and one kilogram of steel.
The person i’m Arguing with states that one kilogram of feathers will be lighter when weighed against the one kilogram of steel because the feathers are more buoyant.
She has done her calculations for the density of feathers and works out that 1 kilogram of feathers will displace 400 litres of water. And because the feathers are more buoyant than the steel they would actually weigh less.
We are talking about a kilogram of feathers as mass, not weight.
The argument goes that if a scale balanced perfectly in a vacuum, it would not in air. The feathers being more buoyant in air would cause the scale to tip towards the steel.
I’m sure she is wrong, and even though buoyancy may be a factor, she calculates that the feathers would only be almost half their weight in air than they are in a vacuum.
So the question is...
If equal masses of 1 kilogram of feathers and steel were balanced in a vacuum, would they still balance in 1 atmosphere. And what would be the difference in weight?
Can you help me resolve this and tell me if buoyancy is a factor, and if so by how much?
Thank you.
mass
asked 5 hours ago
James Thorpe
313
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add a comment |
up vote
6
down vote
favorite
I’m really really sorry about this but i’m Having a discussion at the moment regarding a mass of one kilogram of feathers and one kilogram of steel.
The person i’m Arguing with states that one kilogram of feathers will be lighter when weighed against the one kilogram of steel because the feathers are more buoyant.
She has done her calculations for the density of feathers and works out that 1 kilogram of feathers will displace 400 litres of water. And because the feathers are more buoyant than the steel they would actually weigh less.
We are talking about a kilogram of feathers as mass, not weight.
The argument goes that if a scale balanced perfectly in a vacuum, it would not in air. The feathers being more buoyant in air would cause the scale to tip towards the steel.
I’m sure she is wrong, and even though buoyancy may be a factor, she calculates that the feathers would only be almost half their weight in air than they are in a vacuum.
So the question is...
If equal masses of 1 kilogram of feathers and steel were balanced in a vacuum, would they still balance in 1 atmosphere. And what would be the difference in weight?
Can you help me resolve this and tell me if buoyancy is a factor, and if so by how much?
Thank you.
mass
asked 5 hours ago
James Thorpe
313
New contributor
James Thorpe is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Do the test in water
– user6760
4 hours ago
add a comment |
up vote
6
down vote
favorite
up vote
6
down vote
favorite
I’m really really sorry about this but i’m Having a discussion at the moment regarding a mass of one kilogram of feathers and one kilogram of steel.
The person i’m Arguing with states that one kilogram of feathers will be lighter when weighed against the one kilogram of steel because the feathers are more buoyant.
She has done her calculations for the density of feathers and works out that 1 kilogram of feathers will displace 400 litres of water. And because the feathers are more buoyant than the steel they would actually weigh less.
We are talking about a kilogram of feathers as mass, not weight.
The argument goes that if a scale balanced perfectly in a vacuum, it would not in air. The feathers being more buoyant in air would cause the scale to tip towards the steel.
I’m sure she is wrong, and even though buoyancy may be a factor, she calculates that the feathers would only be almost half their weight in air than they are in a vacuum.
So the question is...
If equal masses of 1 kilogram of feathers and steel were balanced in a vacuum, would they still balance in 1 atmosphere. And what would be the difference in weight?
Can you help me resolve this and tell me if buoyancy is a factor, and if so by how much?
Thank you.
mass
asked 5 hours ago
James Thorpe
313
New contributor
James Thorpe is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I’m really really sorry about this but i’m Having a discussion at the moment regarding a mass of one kilogram of feathers and one kilogram of steel.
The person i’m Arguing with states that one kilogram of feathers will be lighter when weighed against the one kilogram of steel because the feathers are more buoyant.
She has done her calculations for the density of feathers and works out that 1 kilogram of feathers will displace 400 litres of water. And because the feathers are more buoyant than the steel they would actually weigh less.
We are talking about a kilogram of feathers as mass, not weight.
The argument goes that if a scale balanced perfectly in a vacuum, it would not in air. The feathers being more buoyant in air would cause the scale to tip towards the steel.
I’m sure she is wrong, and even though buoyancy may be a factor, she calculates that the feathers would only be almost half their weight in air than they are in a vacuum.
So the question is...
If equal masses of 1 kilogram of feathers and steel were balanced in a vacuum, would they still balance in 1 atmosphere. And what would be the difference in weight?
Can you help me resolve this and tell me if buoyancy is a factor, and if so by how much?
Thank you.
mass
mass
asked 5 hours ago
James Thorpe
313
New contributor
James Thorpe is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 5 hours ago
James Thorpe
313
New contributor
James Thorpe is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 4 hours ago
asked 5 hours ago
James Thorpe
313
New contributor
James Thorpe is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 5 hours ago
James Thorpe
313
asked 5 hours ago
James Thorpe
313
313
New contributor
James Thorpe is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
James Thorpe is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
James Thorpe is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Do the test in water
– user6760
4 hours ago
add a comment |
Do the test in water
– user6760
4 hours ago
Do the test in water
– user6760
4 hours ago
Do the test in water
– user6760
4 hours ago
add a comment |
3 Answers
3
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oldest
votes
up vote
5
down vote
Feathers are made from keratin, with a density of about 1.3 grams/cc. The net volume displaced by a kilogram of feathers is then 751 cc's. Steel has a density of 7.86 g/cc and a kilogram of it displaces 127 cc's.
Sea level air has a density of 0.0012 g/cc, so the buoyant force on 751 cc's of keratin is then 0.92 grams and the buoyant force on 127 cc's of steel is 0.155 grams.
This means that if we weigh the keratin in a vacuum, it will weigh 1 kilogram but in air it will weigh 999.08 grams. If we weigh the steel in a vacuum, it will weigh 1 kilogram but in air it will weigh 999.85 grams.
If we place the two bodies- keratin and steel, one kg of each- on a pivoting balance equidistant from the pivot in a vacuum, they will be in balance, but in air the keratin will be lighter by (999.85-999.08) grams or 0.77 grams.
answered 1 hour ago
niels nielsen
15.3k42649
add a comment |
up vote
1
down vote
You can argue that her feathers contain a lot of air (never perfectly compressed) so that the volume is not true. You could also take your kilo of steel and make it into a hollow sphere (empty) of the same volume as the feathers (whatever that is) and then it would actually weigh less because you have no air inside. But you could be nice and let her make the point about a bigger volume being more bouyant, she is correct about this but ..... even volume is tricky.
answered 4 hours ago
PhysicsDave
80536
The argument is not that buoyancy makes no difference, it is the amount of difference it makes that is in dispute. She is arguing that the buoyancy of the feathers is related to the density of feathers in the bag including the air within. This I do not agree with. She calculates that it’s buoyancy would make it weigh almost half of what it would weigh in a vacuum. I do not agree with either of these figures.
– James Thorpe
2 hours ago
She also calculates that a mass of one kilogram of feathers would displace 400 litres of water if immersed. I do not agree with that figure either.
– James Thorpe
2 hours ago
Yes good points.
– PhysicsDave
23 mins ago
add a comment |
up vote
-2
down vote
Due to buoyancy one kilogram of hot air balloon indeed weighs less than one kilogram of steel!
answered 5 hours ago
my2cts
4,3502617
It would be nice if you told us by how much, haha.
– FGSUZ
5 hours ago
This would be better as a comment
– Aaron Stevens
4 hours ago
I have used the above to elaborate on the question. Thanks.
– James Thorpe
4 hours ago
add a comment |
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3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
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active
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active
oldest
votes
up vote
5
down vote
Feathers are made from keratin, with a density of about 1.3 grams/cc. The net volume displaced by a kilogram of feathers is then 751 cc's. Steel has a density of 7.86 g/cc and a kilogram of it displaces 127 cc's.
Sea level air has a density of 0.0012 g/cc, so the buoyant force on 751 cc's of keratin is then 0.92 grams and the buoyant force on 127 cc's of steel is 0.155 grams.
This means that if we weigh the keratin in a vacuum, it will weigh 1 kilogram but in air it will weigh 999.08 grams. If we weigh the steel in a vacuum, it will weigh 1 kilogram but in air it will weigh 999.85 grams.
If we place the two bodies- keratin and steel, one kg of each- on a pivoting balance equidistant from the pivot in a vacuum, they will be in balance, but in air the keratin will be lighter by (999.85-999.08) grams or 0.77 grams.
answered 1 hour ago
niels nielsen
15.3k42649
add a comment |
up vote
5
down vote
Feathers are made from keratin, with a density of about 1.3 grams/cc. The net volume displaced by a kilogram of feathers is then 751 cc's. Steel has a density of 7.86 g/cc and a kilogram of it displaces 127 cc's.
Sea level air has a density of 0.0012 g/cc, so the buoyant force on 751 cc's of keratin is then 0.92 grams and the buoyant force on 127 cc's of steel is 0.155 grams.
This means that if we weigh the keratin in a vacuum, it will weigh 1 kilogram but in air it will weigh 999.08 grams. If we weigh the steel in a vacuum, it will weigh 1 kilogram but in air it will weigh 999.85 grams.
If we place the two bodies- keratin and steel, one kg of each- on a pivoting balance equidistant from the pivot in a vacuum, they will be in balance, but in air the keratin will be lighter by (999.85-999.08) grams or 0.77 grams.
answered 1 hour ago
niels nielsen
15.3k42649
add a comment |
up vote
5
down vote
up vote
5
down vote
Feathers are made from keratin, with a density of about 1.3 grams/cc. The net volume displaced by a kilogram of feathers is then 751 cc's. Steel has a density of 7.86 g/cc and a kilogram of it displaces 127 cc's.
Sea level air has a density of 0.0012 g/cc, so the buoyant force on 751 cc's of keratin is then 0.92 grams and the buoyant force on 127 cc's of steel is 0.155 grams.
This means that if we weigh the keratin in a vacuum, it will weigh 1 kilogram but in air it will weigh 999.08 grams. If we weigh the steel in a vacuum, it will weigh 1 kilogram but in air it will weigh 999.85 grams.
If we place the two bodies- keratin and steel, one kg of each- on a pivoting balance equidistant from the pivot in a vacuum, they will be in balance, but in air the keratin will be lighter by (999.85-999.08) grams or 0.77 grams.
answered 1 hour ago
niels nielsen
15.3k42649
Feathers are made from keratin, with a density of about 1.3 grams/cc. The net volume displaced by a kilogram of feathers is then 751 cc's. Steel has a density of 7.86 g/cc and a kilogram of it displaces 127 cc's.
Sea level air has a density of 0.0012 g/cc, so the buoyant force on 751 cc's of keratin is then 0.92 grams and the buoyant force on 127 cc's of steel is 0.155 grams.
This means that if we weigh the keratin in a vacuum, it will weigh 1 kilogram but in air it will weigh 999.08 grams. If we weigh the steel in a vacuum, it will weigh 1 kilogram but in air it will weigh 999.85 grams.
If we place the two bodies- keratin and steel, one kg of each- on a pivoting balance equidistant from the pivot in a vacuum, they will be in balance, but in air the keratin will be lighter by (999.85-999.08) grams or 0.77 grams.
answered 1 hour ago
niels nielsen
15.3k42649
edited 54 mins ago
answered 1 hour ago
niels nielsen
15.3k42649
answered 1 hour ago
niels nielsen
15.3k42649
answered 1 hour ago
niels nielsen
15.3k42649
15.3k42649
add a comment |
add a comment |
up vote
1
down vote
You can argue that her feathers contain a lot of air (never perfectly compressed) so that the volume is not true. You could also take your kilo of steel and make it into a hollow sphere (empty) of the same volume as the feathers (whatever that is) and then it would actually weigh less because you have no air inside. But you could be nice and let her make the point about a bigger volume being more bouyant, she is correct about this but ..... even volume is tricky.
answered 4 hours ago
PhysicsDave
80536
The argument is not that buoyancy makes no difference, it is the amount of difference it makes that is in dispute. She is arguing that the buoyancy of the feathers is related to the density of feathers in the bag including the air within. This I do not agree with. She calculates that it’s buoyancy would make it weigh almost half of what it would weigh in a vacuum. I do not agree with either of these figures.
– James Thorpe
2 hours ago
She also calculates that a mass of one kilogram of feathers would displace 400 litres of water if immersed. I do not agree with that figure either.
– James Thorpe
2 hours ago
Yes good points.
– PhysicsDave
23 mins ago
add a comment |
up vote
1
down vote
You can argue that her feathers contain a lot of air (never perfectly compressed) so that the volume is not true. You could also take your kilo of steel and make it into a hollow sphere (empty) of the same volume as the feathers (whatever that is) and then it would actually weigh less because you have no air inside. But you could be nice and let her make the point about a bigger volume being more bouyant, she is correct about this but ..... even volume is tricky.
answered 4 hours ago
PhysicsDave
80536
The argument is not that buoyancy makes no difference, it is the amount of difference it makes that is in dispute. She is arguing that the buoyancy of the feathers is related to the density of feathers in the bag including the air within. This I do not agree with. She calculates that it’s buoyancy would make it weigh almost half of what it would weigh in a vacuum. I do not agree with either of these figures.
– James Thorpe
2 hours ago
She also calculates that a mass of one kilogram of feathers would displace 400 litres of water if immersed. I do not agree with that figure either.
– James Thorpe
2 hours ago
Yes good points.
– PhysicsDave
23 mins ago
add a comment |
up vote
1
down vote
up vote
1
down vote
You can argue that her feathers contain a lot of air (never perfectly compressed) so that the volume is not true. You could also take your kilo of steel and make it into a hollow sphere (empty) of the same volume as the feathers (whatever that is) and then it would actually weigh less because you have no air inside. But you could be nice and let her make the point about a bigger volume being more bouyant, she is correct about this but ..... even volume is tricky.
answered 4 hours ago
PhysicsDave
80536
You can argue that her feathers contain a lot of air (never perfectly compressed) so that the volume is not true. You could also take your kilo of steel and make it into a hollow sphere (empty) of the same volume as the feathers (whatever that is) and then it would actually weigh less because you have no air inside. But you could be nice and let her make the point about a bigger volume being more bouyant, she is correct about this but ..... even volume is tricky.
answered 4 hours ago
PhysicsDave
80536
answered 4 hours ago
PhysicsDave
80536
answered 4 hours ago
PhysicsDave
80536
answered 4 hours ago
PhysicsDave
80536
80536
The argument is not that buoyancy makes no difference, it is the amount of difference it makes that is in dispute. She is arguing that the buoyancy of the feathers is related to the density of feathers in the bag including the air within. This I do not agree with. She calculates that it’s buoyancy would make it weigh almost half of what it would weigh in a vacuum. I do not agree with either of these figures.
– James Thorpe
2 hours ago
She also calculates that a mass of one kilogram of feathers would displace 400 litres of water if immersed. I do not agree with that figure either.
– James Thorpe
2 hours ago
Yes good points.
– PhysicsDave
23 mins ago
add a comment |
The argument is not that buoyancy makes no difference, it is the amount of difference it makes that is in dispute. She is arguing that the buoyancy of the feathers is related to the density of feathers in the bag including the air within. This I do not agree with. She calculates that it’s buoyancy would make it weigh almost half of what it would weigh in a vacuum. I do not agree with either of these figures.
– James Thorpe
2 hours ago
She also calculates that a mass of one kilogram of feathers would displace 400 litres of water if immersed. I do not agree with that figure either.
– James Thorpe
2 hours ago
Yes good points.
– PhysicsDave
23 mins ago
The argument is not that buoyancy makes no difference, it is the amount of difference it makes that is in dispute. She is arguing that the buoyancy of the feathers is related to the density of feathers in the bag including the air within. This I do not agree with. She calculates that it’s buoyancy would make it weigh almost half of what it would weigh in a vacuum. I do not agree with either of these figures.
– James Thorpe
2 hours ago
The argument is not that buoyancy makes no difference, it is the amount of difference it makes that is in dispute. She is arguing that the buoyancy of the feathers is related to the density of feathers in the bag including the air within. This I do not agree with. She calculates that it’s buoyancy would make it weigh almost half of what it would weigh in a vacuum. I do not agree with either of these figures.
– James Thorpe
2 hours ago
She also calculates that a mass of one kilogram of feathers would displace 400 litres of water if immersed. I do not agree with that figure either.
– James Thorpe
2 hours ago
She also calculates that a mass of one kilogram of feathers would displace 400 litres of water if immersed. I do not agree with that figure either.
– James Thorpe
2 hours ago
Yes good points.
– PhysicsDave
23 mins ago
Yes good points.
– PhysicsDave
23 mins ago
add a comment |
up vote
-2
down vote
Due to buoyancy one kilogram of hot air balloon indeed weighs less than one kilogram of steel!
answered 5 hours ago
my2cts
4,3502617
It would be nice if you told us by how much, haha.
– FGSUZ
5 hours ago
This would be better as a comment
– Aaron Stevens
4 hours ago
I have used the above to elaborate on the question. Thanks.
– James Thorpe
4 hours ago
add a comment |
up vote
-2
down vote
Due to buoyancy one kilogram of hot air balloon indeed weighs less than one kilogram of steel!
answered 5 hours ago
my2cts
4,3502617
It would be nice if you told us by how much, haha.
– FGSUZ
5 hours ago
This would be better as a comment
– Aaron Stevens
4 hours ago
I have used the above to elaborate on the question. Thanks.
– James Thorpe
4 hours ago
add a comment |
up vote
-2
down vote
up vote
-2
down vote
Due to buoyancy one kilogram of hot air balloon indeed weighs less than one kilogram of steel!
answered 5 hours ago
my2cts
4,3502617
Due to buoyancy one kilogram of hot air balloon indeed weighs less than one kilogram of steel!
answered 5 hours ago
my2cts
4,3502617
answered 5 hours ago
my2cts
4,3502617
answered 5 hours ago
my2cts
4,3502617
answered 5 hours ago
my2cts
4,3502617
4,3502617
It would be nice if you told us by how much, haha.
– FGSUZ
5 hours ago
This would be better as a comment
– Aaron Stevens
4 hours ago
I have used the above to elaborate on the question. Thanks.
– James Thorpe
4 hours ago
add a comment |
It would be nice if you told us by how much, haha.
– FGSUZ
5 hours ago
This would be better as a comment
– Aaron Stevens
4 hours ago
I have used the above to elaborate on the question. Thanks.
– James Thorpe
4 hours ago
It would be nice if you told us by how much, haha.
– FGSUZ
5 hours ago
It would be nice if you told us by how much, haha.
– FGSUZ
5 hours ago
This would be better as a comment
– Aaron Stevens
4 hours ago
This would be better as a comment
– Aaron Stevens
4 hours ago
I have used the above to elaborate on the question. Thanks.
– James Thorpe
4 hours ago
I have used the above to elaborate on the question. Thanks.
– James Thorpe
4 hours ago
add a comment |
James Thorpe is a new contributor. Be nice, and check out our Code of Conduct.
James Thorpe is a new contributor. Be nice, and check out our Code of Conduct.
James Thorpe is a new contributor. Be nice, and check out our Code of Conduct.
James Thorpe is a new contributor. Be nice, and check out our Code of Conduct.
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Do the test in water
– user6760
4 hours ago