# The Naked Scientists Forum

### Author Topic: If the Kilogram is the constant for Mass, how much Mass is in 5lbs of U235?  (Read 3234 times)

#### Joe L. Ogan

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##### If the Kilogram is the constant for Mass, how much Mass is in 5lbs of U235?
« on: 20/01/2010 13:35:58 »
If the Kilogram is the constant for Mass, how much Mass is in 5 lbs of U235?  The weight of the Kilogram is changing.  Science is attempting to establish a new standard for the Kilogram.  But using the old weight of a Kilogram please work out the equation E=mc2.  Please show how you work out the equation.  Thanks for comments.  Joe L. Ogan

#### Joe L. Ogan

• Sr. Member
• Posts: 476
##### If the Kilogram is the constant for Mass, how much Mass is in 5lbs of U235?
« Reply #1 on: 20/01/2010 15:27:41 »
Here is something that I have found out.  It takes about 15 pounds of U 235 to make an atomic bomb.  15 pounds of U 235 is equal to 7 Kilograms of mass.  So  in an Atomic bomb of this size, Energy would be equal to 7 Kilograms (mass) times the speed of light squared.  It would then be expressed in Joules.  Thanks for comments.  Joe L. Ogan
« Last Edit: 20/01/2010 18:00:45 by Joe L. Ogan »

#### syhprum

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##### If the Kilogram is the constant for Mass, how much Mass is in 5lbs of U235?
« Reply #2 on: 20/01/2010 16:32:14 »
If you really wish to make a gun type U235 nuclear bomb I suggest you study this

http://en.wikipedia.org/wiki/Little_Boy

I believe about 2% of energy inherent in the 64Kg U235 was converted into 'useful' enegy
« Last Edit: 20/01/2010 17:12:36 by syhprum »

#### Bored chemist

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##### If the Kilogram is the constant for Mass, how much Mass is in 5lbs of U235?
« Reply #3 on: 20/01/2010 19:02:36 »
5 pounds = 2.26796185 kilograms
It doesn't matter that it's uranium or what.

"15 pounds of U 235 is equal to 7 Kilograms of mass"
No it isn't.

" But using the old weight of a Kilogram "
Weight of a kilogram where; on earth, on the moon, "in zero" gravity?

#### Joe L. Ogan

• Sr. Member
• Posts: 476
##### If the Kilogram is the constant for Mass, how much Mass is in 5lbs of U235?
« Reply #4 on: 20/01/2010 19:20:33 »
Those are the weights that were given to me when I checked on Kilogram.  I do not vouch for their accuracy but, in any event, they are rather close.  What do you say that 15 pounds of U 258 will be expressed in Kilograms?  Thanks for comments. Joe L. Ogan

#### LeeE

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##### If the Kilogram is the constant for Mass, how much Mass is in 5lbs of U235?
« Reply #5 on: 20/01/2010 19:32:43 »
The kilogram isn't a constant, just a standard measure.  It's exactly the same as measuring distance; you can do it in feet & inches, miles, nautical miles, metres or kilometres.

They're all just different sized units to measure with.  The reason that the kilogram has become a 'standard' is that it's decimal based, which makes it easy for us to do maths with, and that its size works nicely with the other SI units.  For example, if 1kg of flour costs 1\$, then one tenth of a kg of flour would cost \$0.1, but if you used the old UKP Sterling and 2lb of flour cost £1 then one tenth of 2lb is 3 ounces, 87.5 grains, and it would cost you two shillings, or 24 pence.

#### Joe L. Ogan

• Sr. Member
• Posts: 476
##### If the Kilogram is the constant for Mass, how much Mass is in 5lbs of U235?
« Reply #6 on: 20/01/2010 20:39:45 »
The kilogram isn't a constant, just a standard measure.  It's exactly the same as measuring distance; you can do it in feet & inches, miles, nautical miles, metres or kilometres.

They're all just different sized units to measure with.  The reason that the kilogram has become a 'standard' is that it's decimal based, which makes it easy for us to do maths with, and that its size works nicely with the other SI units.  For example, if 1kg of flour costs 1\$, then one tenth of a kg of flour would cost \$0.1, but if you used the old UKP Sterling and 2lb of flour cost £1 then one tenth of 2lb is 3 ounces, 87.5 grains, and it would cost you two shillings, or 24 pence.

Hi, Lee.  On the internet, the kilogram is stated as a constant for Mass.  Perhaps that is wrong.  There is much on the internet that is wrong.  There is much in standard text books that is wrong also.  That is why one must continue to question what they think they know.  I appreciate your comments.  Joe L. Ogan

#### Joe L. Ogan

• Sr. Member
• Posts: 476
##### If the Kilogram is the constant for Mass, how much Mass is in 5lbs of U235?
« Reply #7 on: 20/01/2010 22:26:07 »
5 pounds = 2.26796185 kilograms
It doesn't matter that it's uranium or what.

"15 pounds of U 235 is equal to 7 Kilograms of mass"
No it isn't.

" But using the old weight of a Kilogram "
Weight of a kilogram where; on earth, on the moon, "in zero" gravity?

The kilogram that is used to measure all kilograms is losing weight and scientists are concerned as the Kilogram is used in so many different measures in Scientific endeavors.  They believe it is losing weight because it is cleaned and they think that rubbing it is causing it to lose weight.  Thanks for comments.  Joe L. Ogan

#### Joe L. Ogan

• Sr. Member
• Posts: 476
##### If the Kilogram is the constant for Mass, how much Mass is in 5lbs of U235?
« Reply #8 on: 20/01/2010 22:37:53 »
5 pounds = 2.26796185 kilograms
It doesn't matter that it's uranium or what.

"15 pounds of U 235 is equal to 7 Kilograms of mass"
No it isn't.  OK, I looked it up and 15 pounds is equal to 6.80388 kilograms.  I guess that the reference that gave me 7 pounds rounded off the figure.  Thanks for your comments.  Joe L. Ogan

" But using the old weight of a Kilogram "
Weight of a kilogram where; on earth, on the moon, "in zero" gravity?

The kilogram that is used to measure all kilograms is losing weight and scientists are concerned as the Kilogram is used in so many different measures in Scientific endeavors.  They believe it is losing weight because it is cleaned and they think that rubbing it is causing it to lose weight.  Thanks for comments.  Joe L. Ogan

#### Bored chemist

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##### If the Kilogram is the constant for Mass, how much Mass is in 5lbs of U235?
« Reply #9 on: 21/01/2010 18:58:31 »
It is true that the international prototype kilogram is changing mass. That's a bit of a problem but, since the legal definition of the pound is expressed in terms of the kilogram 5 lbs is still 2.26796185 kilograms.

« Last Edit: 21/01/2010 19:11:24 by Bored chemist »

#### The Naked Scientists Forum

##### If the Kilogram is the constant for Mass, how much Mass is in 5lbs of U235?
« Reply #9 on: 21/01/2010 18:58:31 »