# Relativistic Momentum Remains a Vector When in the context of Relativistic Energy?

1. Jul 25, 2011

### jaketodd

Relativistic momentum is a vector, just as non-relativistic momentum is a vector, right? Part of the relativistic energy equation includes relativistic momentum. See here please: http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/releng.html" [Broken]

Could the relativistic momentum energy part of the relativistic energy equation be considered as a vector when the equation is computed for total relativistic energy? That is, does relativistic momentum, when taken in the context of relativistic energy as a whole, still have a vector? The answer to this question must be yes, because otherwise, without a vector for some of the relativistic energy, then the object would remain stationary. Another question please: I suppose the relativistic momentum could do without a vector in the context of relativistic energy, but then what would keep the object going...Is the relativistic kinetic energy portion of total relativistic energy a vector? Or, are both relativistic kinetic energy, and relativistic momentum, vectors in the context of computed relativistic energy? Or, I suppose you could simply say: Does relativistic energy, as a whole, have a vector component or components, and if so, what part of the relativistic energy has this/these vectors? Maybe this could sum it up: Relativistic energy must have some vector component because otherwise the object would be stationary, right?

Many Thanks,

Jake :zzz:

Last edited by a moderator: May 5, 2017
2. Jul 25, 2011

### bcrowell

Staff Emeritus
Re: Relativistic Momentum Remains a Vector When in the context of Relativistic Energy

It sounds like you're asking about the energy-momentum four-vector: http://en.wikipedia.org/wiki/Four-momentum The hyperphysics link you gave doesn't seem to discuss it.

3. Jul 27, 2011

### jaketodd

Re: Relativistic Momentum Remains a Vector When in the context of Relativistic Energy

Very good; thank you! Another question please: Is there such a thing as four-kinetic energy?

4. Jul 27, 2011

### bcrowell

Staff Emeritus
Re: Relativistic Momentum Remains a Vector When in the context of Relativistic Energy

The fact that you're asking that question makes me think that you haven't read the WP article yet...?

5. Jul 27, 2011

### jaketodd

Re: Relativistic Momentum Remains a Vector When in the context of Relativistic Energy

So you're talking about four-velocity? I'm not sure if that creates four-kinetic energy or just goes into four-momentum.

Thanks!

Jake

6. Jul 29, 2011

### jaketodd

Re: Relativistic Momentum Remains a Vector When in the context of Relativistic Energy

7. Jul 29, 2011

### pervect

Staff Emeritus
Re: Relativistic Momentum Remains a Vector When in the context of Relativistic Energy

Did you read the wiki yet? If so, what's your current understanding of the energy-momentum 4 vector?

If not - do you have some reason why not?

8. Jul 31, 2011

### jaketodd

Re: Relativistic Momentum Remains a Vector When in the context of Relativistic Energy

I think I understand it now. I think I just needed to read the article a couple more times for it to set.

Thanks,

Jake