[Minor Page Change] A speed value is a little wrong (again).

[SeijiSetto]

hi
this page says Relativistic Kinetic Energy is 4x higher than Newtonian KE at 93% SoL.
this is not true, it happens at ~96.82458% SoL, take your choice of significant figures.
idk if i have to make a thread for this or if i could have just asked a content mod to unlock it for like 5 minutes but we're here now so

 

[XSOULOFCINDERX]

I'm not good at math whatsoever but if it's that simple of a fix then go for it.

 

[Antvasima]

@DontTalkDT

What do you think should be done here?

 

[SeijiSetto]

@DontTalkDT

What do you think should be done here?

not in a rude way or anything but
why does DT need to be consulted here?
this is just a minor change that makes sure that the page is actually consistent in what it's saying.
it caps Relativistic KE at 4x higher than the Newtonian value. this happens at 0.9682c instead of 0.93c, which is what the page currently says.
i don't think this needs any approval besides a second pair of eyes making sure i didn't fuck up my math, which i'm pretty confident i didn't.

 

[Antvasima]

Well, I just want to make sure that he is fine with that we should change the 0.93c value rather than the 4x value, as it might mess up some of our currently accepted calculation blogs otherwise.

 

[DontTalkDT]

Rel.KE = (1/sqrt(1-v^2/c^2) -1) * m * c^2
KE = 0.5*m*v^2

Rel.KE/KE = 4
<=>
((1/sqrt(1-v^2/c^2) -1) * m * c^2) / (0.5*m*v^2) = 4
<=>
((1/sqrt(1-v^2/c^2) -1) * c^2) / (0.5*v^2) = 4

Speed of light = c = 299 792 458 m/s.
That gives v = 2.78988×10^8 m/s.
Ratio = 2.78988×10^8 / 299 792 458 = 0.93

Or am I mistaken at some point? Can you show your derivation?

 

[SeijiSetto]

Rel.KE = (1/sqrt(1-v^2/c^2) -1) * m * c^2
KE = 0.5*m*v^2

Rel.KE/KE = 4
<=>
((1/sqrt(1-v^2/c^2) -1) * m * c^2) / (0.5*m*v^2) = 4
<=>
((1/sqrt(1-v^2/c^2) -1) * c^2) / (0.5*v^2) = 4

Speed of light = c = 299 792 458 m/s.
That gives v = 2.78988×10^8 m/s.
Ratio = 2.78988×10^8 / 299 792 458 = 0.93

Or am I mistaken at some point? Can you show your derivation?

just to clarify, your rel KE formula (what you wrote on the first line) is this, right?

 

[DontTalkDT]

Yes