Can someone explain mass energy conservation?

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Discussion Overview

The discussion revolves around the concept of mass-energy conservation, particularly how mass can transform into energy and vice versa. Participants explore theoretical implications and examples, including nuclear fusion and the effects of potential energy on mass perception.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about how mass can become energy and vice versa, seeking alternative explanations.
  • Another participant provides an example of nuclear fusion, stating that two masses combine to a lesser mass and release energy, suggesting that mass and energy are conserved overall.
  • A participant questions how gaining energy, such as when moving in a lift, could result in an increase in mass, pondering whether energy can be considered as matter.
  • Another participant references the work-energy theorem, indicating that the increase in mass due to velocity and gravitational potential is balanced by the work done in those scenarios.
  • A later reply indicates a sense of understanding after the discussion, though it does not clarify the initial confusion fully.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the nature of mass-energy transformation, with ongoing questions about the relationship between energy gain and mass increase remaining unresolved.

Contextual Notes

There are limitations in the discussion regarding the definitions of mass and energy, as well as the assumptions underlying the examples provided, particularly in relation to relativistic effects and potential energy.

matt_crouch
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Im confused with mass energy conservation. i get that mass and energy are conserved but i don't understand how mass can become energy and visa versa.. can anyone help explain it to me in another way?
 
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Welcome to PF!

matt_crouch said:
Im confused with mass energy conservation. i get that mass and energy are conserved but i don't understand how mass can become energy and visa versa.. can anyone help explain it to me in another way?

Hi matt_crouch! Welcome to PF! :smile:

An example: in nuclear fusion, two masses combine to a lesser mass and give off energy.

The mass-plus-energy is the same before as after. :smile:
 
But what i find confussing is how can someone get heavier as they gain energy. for example someone going up in a lift gains potential energy and mass?

are they gaining matter? or can energy be matter.. if u see what I am getting it. how can a gain in energy cause a gain in kilograms.

im probably just makeing it more confusing =]
 
The work-energy theorem still applies …

the special relativistic increase in mass due to velocity is balanced by the work done in increasing the speed

and the general relativistic increase in mass due to lower gravitational potential is balanced by the work done by gravity. :smile:
 
ahh ok i get it.. i think cheers for the help :D
 

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