What is the relationship between kg wt and Newtons through dimensional analysis?

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Discussion Overview

The discussion revolves around the relationship between kilogram weight (kg wt) and Newtons (N) through dimensional analysis. Participants explore the definitions and mathematical derivations related to these units of force, particularly in the context of gravitational acceleration on Earth.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant expresses confusion about the relationship 1 kg wt = 9.8 N and attempts to use dimensional analysis to understand it.
  • Another participant clarifies that kilogram weight is a unit of force, defined as the force required to accelerate a mass of 1 kg at 9.80665 m/s².
  • There is a repeated inquiry about deriving the relation mathematically, indicating a desire for a formal explanation.
  • One participant states that the relation cannot be derived, emphasizing that kilogram-force is defined based on gravitational acceleration.
  • Another participant provides a calculation showing that the weight of a 1 kg mass on Earth is 9.81 N, reinforcing the definition of kg wt as a unit of force.
  • One participant acknowledges understanding after receiving explanations about the definitions and calculations involved.

Areas of Agreement / Disagreement

Participants generally agree on the definition of kilogram weight as a unit of force related to gravitational acceleration. However, there is some disagreement regarding the ability to derive the relationship mathematically, with differing opinions on whether a formal derivation is possible.

Contextual Notes

The discussion includes assumptions about gravitational acceleration being approximately 9.81 m/s², which may vary based on location. There is also a lack of consensus on the derivation of the relationship between kg wt and Newtons.

sphyics
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i know its a unit for force... I'm intrigued by the relation 1kgwt=9.8N?

by dimensional analysis

L.H.s [M2L1T-2 {since wt=kgm/s2}
R.H.S [M1L1T-2
i understand I'm wrong somewhere, but I'm not able to figure it out, so pls help me :)

Also how to get the relation between both.( think 9.8 is the contribution of 'g')
 
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sphyics said:
i know its a unit for force... I'm intrigued by the relation 1kgwt=9.8N?

by dimensional analysis

L.H.s [M2L1T-2 {since wt=kgm/s2}

You interpreted kg wt as mass*weight. A kilogram weight is a unit of force. Specifically, it is the force needed to make a mass of 1 kg accelerate by 9.80665 m/s2.
 
D H said:
You interpreted kg wt as mass*weight. A kilogram weight is a unit of force. Specifically, it is the force needed to make a mass of 1 kg accelerate by 9.80665 m/s2.
yes

and how to get the relation 1kgwt=9.8N mathematically.
 
You can't derive it. The kilogram-force (sometimes called the kilogram-wt) is defined as the force needed to make a one kilogram of mass accelerate by 9.80665 m/s2.
 
sphyics said:
how to get the relation 1kgwt=9.8N mathematically.

1 kgwt means the "weight of a mass of 1 kg on earth". So:

W = ma = (1 kg)(9.81 m/s²) = 9.81 N = 1 kgwt

kgwt is an arbitrary defined unit for force, just like 1 lb = 4.448 N
 
jack action said:
1 kgwt means the "weight of a mass of 1 kg on earth". So:

W = ma = (1 kg)(9.81 m/s²) = 9.81 N = 1 kgwt

kgwt is an arbitrary defined unit for force, just like 1 lb = 4.448 N

Thanks for ur explanation now i understand
 

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