Physics Help Forum unit of weight

 Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum

 Nov 18th 2008, 08:09 AM #1 Junior Member   Join Date: Nov 2008 Posts: 3 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?
 Nov 21st 2008, 05:10 AM #2 Junior Member   Join Date: Nov 2008 Posts: 5 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. Physics Complete
 Nov 22nd 2008, 05:44 AM #3 Junior Member   Join Date: Nov 2008 Posts: 3 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?
 Nov 22nd 2008, 06:15 AM #4 Senior Member     Join Date: Apr 2008 Posts: 815 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. __________________ Isaac If the problem is too hard just let the Universe solve it.
 Nov 23rd 2008, 01:36 AM #5 Junior Member   Join Date: Nov 2008 Posts: 5 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. Physics Complete
Nov 23rd 2008, 04:34 AM   #6
Senior Member

Join Date: Apr 2008
Posts: 815
 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.
__________________
Isaac
If the problem is too hard just let the Universe solve it.

 Tags unit, weight

 Thread Tools Display Modes Linear Mode

 Similar Physics Forum Discussions Thread Thread Starter Forum Replies Last Post mitnord Thermodynamics and Fluid Mechanics 1 Mar 10th 2009 10:41 AM zebra1707 Electricity and Magnetism 1 Dec 4th 2008 06:53 AM chocolatelover Kinematics and Dynamics 2 Sep 23rd 2008 05:28 AM topsquark Physics Resources 0 Apr 11th 2008 08:31 AM