Editing Talk:2073: Kilogram
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:But how do you define/measure a Joule then? [[User:Fabian42|Fabian42]] ([[User talk:Fabian42|talk]]) 18:19, 16 November 2018 (UTC) | :But how do you define/measure a Joule then? [[User:Fabian42|Fabian42]] ([[User talk:Fabian42|talk]]) 18:19, 16 November 2018 (UTC) | ||
:No, until 1964, meter and litre were totally independent, a meter has never been defined directly or indirectly in relation to a mass of water. It is only since 1964 that the liter is defined as a cubic decimeter.[[Special:Contributions/162.158.90.36|162.158.90.36]] 18:36, 16 November 2018 (UTC) | :No, until 1964, meter and litre were totally independent, a meter has never been defined directly or indirectly in relation to a mass of water. It is only since 1964 that the liter is defined as a cubic decimeter.[[Special:Contributions/162.158.90.36|162.158.90.36]] 18:36, 16 November 2018 (UTC) | ||
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:Also, in E=mc², E is the energy '''at rest''' (for a stationary object of mass m), so your definition using the acceleration makes no sense.[[Special:Contributions/162.158.88.254|162.158.88.254]] 18:47, 16 November 2018 (UTC) | :Also, in E=mc², E is the energy '''at rest''' (for a stationary object of mass m), so your definition using the acceleration makes no sense.[[Special:Contributions/162.158.88.254|162.158.88.254]] 18:47, 16 November 2018 (UTC) | ||
::That's not the original intent of that formula though. The modern formula is E=γmc², where m is the rest mass. But when Einstein wrote m in E=mc², he meant mass as in the measure of how much gravitational force you exert and experience... which in modern terms is γm . These days, E=mc² is only valid if γ=1, which translates to a body at rest. But that's due to the convention regarding what is meant by mass (rest mass or effective mass) changing since that formula was written, not the E being intended to neglect relativistic effects. [[Special:Contributions/172.69.55.112|172.69.55.112]] 22:56, 11 September 2019 (UTC) | ::That's not the original intent of that formula though. The modern formula is E=γmc², where m is the rest mass. But when Einstein wrote m in E=mc², he meant mass as in the measure of how much gravitational force you exert and experience... which in modern terms is γm . These days, E=mc² is only valid if γ=1, which translates to a body at rest. But that's due to the convention regarding what is meant by mass (rest mass or effective mass) changing since that formula was written, not the E being intended to neglect relativistic effects. [[Special:Contributions/172.69.55.112|172.69.55.112]] 22:56, 11 September 2019 (UTC) |