Why is a Newton of force .225 pounds?

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Discussion Overview

The discussion revolves around the relationship between Newtons and pounds, specifically why one Newton is approximately equal to 0.225 pounds. Participants explore the definitions of these units of force, their historical context, and the implications of hypothetical scenarios where mass is doubled while gravity remains constant.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions why a Newton is defined as 0.225 pounds, suggesting that if mass were to double, the force required for acceleration would also double, leading to a different ratio.
  • Another participant notes that the definition of a pound has historical roots and is not strictly defined by modern physics, implying that the conversion between pounds and Newtons could vary based on definitions.
  • A third participant emphasizes that the definition of a Newton is consistent across different contexts, being the force needed to accelerate a 1 kg object at 1 m/s², which is independent of location.
  • One participant reiterates the independent definitions of the Newton and the pound-force, acknowledging that the ratio of their values could have been defined differently.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and historical context of force units, with no consensus on why the specific conversion factor exists. The discussion remains unresolved regarding the implications of hypothetical changes to mass and gravity.

Contextual Notes

Participants acknowledge that the definitions of force units are historically and contextually dependent, and the discussion includes speculative elements about how these definitions might change.

Jason DiCaprio
General physics question regarding force and gravity. Hypothetically speaking if every piece of mass weighed double. If something that weighed 1 Pound is now 2 pounds. If you weigh 100 pounds now you weigh 200 pounds . Assume gravity is still 9.8ms/sq. and you never experience gravity any other way Would it then be accepted as the new normal of force. Now a Newton would be equal to .45 pounds force instead of .225. In order to satisfy Newtons law of mass x acceleration = force would then mean that everything would require double the amount of force to accelerate at any rate. A Newton would still be a Newton but the actuaL real measurable force would be double. So my question is why is the actual force for a Newton what it is. ? Why is 1 Newton .224 pound force? Why not 3 pound force , why not 5 why not 100 pound force? I understand however this number increases proportionally it would also increase the actual force for any rate of acceleration on any mass proportionally. So why is the actual real force what it is ? It could be any amount of force and as long as it is satisfied by mass x acceleration it would mean that the force for everything else would be proportionally increased. So basically I am asking why the force to accelerate 1 kg 1 m/s sq which is 1 n of force is .225 pounds why not any other number. (And yes I understand that it would effect the force required to accelerate any mass at any rate of acceleration )
 
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The definition of pound is from ancient languages and (speculative) refers to a weight that will stretch a rope a certain amount. So it is not a modern definition defined by physics. (see definition n.1 in http://www.etymonline.com/index.php?term=pound )

Speculating on how the historical definition of "pound" would change is open to too much debate. Whatever amount of force it would mean, it's conversion to Newtons would be determined by the new ratio of the new definition of a "pound" of force to the standard definition of a Newton of force.
 
Jason DiCaprio said:
Hypothetically speaking if every piece of mass weighed double.

Jason DiCaprio said:
Assume gravity is still 9.8ms/sq
How would you reconcile those two statements?
 
Jason DiCaprio said:
So basically I am asking why the force to accelerate 1 kg 1 m/s sq which is 1 n of force is .225 pounds why not any other number.
As @jedishrfu points out, the pound-force and the Newton are both units of force that were originally defined in totally independent ways. It is a simple matter of measured fact that the one definition yields a quantity that is 0.225 times the other.

Certainly the two units could have been defined differently and the ratio could have been different.
 
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