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Old Nov 18th 2008, 08:09 AM   #1
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Question unit of weight

qus-in common life, why we use kg as unit of weight while its unit is N or m/s2 and kg is unit of mass?
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Old Nov 21st 2008, 05:10 AM   #2
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Unit of weight is newton

Unit of weight is newton only and what you measure in daily life in terms of kilogram is the mass of body.

It is measured with valences where gravity is balanced.

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Old Nov 22nd 2008, 05:44 AM   #3
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Smile thanks

thank u, but please clear me that acc.to ur ans then how the same machine measures wrong mass in freely falling lift &above the surface of moon while mass remains const.i know the reasons of changing the weight with lift &on the moon but if machine measures mass then how could it change?
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Old Nov 22nd 2008, 06:15 AM   #4
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Common balances are calibrated on Earth. Also they have a spring in it which measure weight, they give a result in term of kilograms without doing always a good translation. (It is a good translation only if you are on Earth and even a better one if you are along the equator at sea level).
I give you an example : Say their spring measure 10N. They will say your mass is 98kg, which is almost true on Earth but not on the Moon. On the moon 10N means the object has a mass much greater than 98kg, but as the balance only works with a spring, it cannot know where you are so it always give the result as if you were on Earth.
This is also true if you take an elevator, the balance will give a false result.
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Old Nov 23rd 2008, 01:36 AM   #5
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It seems there is a good confusion between mass and force in your case.

As i mentioned previously mass is the content of a body,quantity of matter and it will never change.

What we measure in lift,or on moon is apparent weight and hence it will change with respect to apparent acceleration.

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Old Nov 23rd 2008, 04:34 AM   #6
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It seems there is a good confusion between mass and force in your case.
Are you talking to me? If yes, show me by quoting me where you think I'm wrong.


As i mentioned previously mass is the content of a body,quantity of matter and it will never change.
I never said the contrary.


What we measure in lift,or on moon is apparent weight and hence it will change with respect to apparent acceleration.
That is exactly what I meant. Read
I give you an example : Say their spring measure 10N. They will say your mass is 98kg, which is almost true on Earth but not on the Moon.
10N is the apparent weight and 98kg is the mass the balance will give but which is not true if on the Moon because on the Moon something that weight 10N has much less mass than 98kg.
I think you misunderstood me and that I'm not confused at all.
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