Energy in different references

[hisham.i]

I was thinking in special relativity and how does the energy look from one reference to another,
if i consider a body making a circular motion in reference R₁, with an angular velocity w₁,and a stationary body in reference R₂, R₁ see that the body in R₂ is rotating with an angular velocity |w₁|, so the body in reference R₂has a kinetic energy 1/2(I*W₁^2) from reference R₂point of view.
But the idea which is puzzling me is: Is this kinetic energy really exist?!

 

[tiny-tim]

Hi hisham.i!

Are you using the rotating body in R₁ as a reference frame?

You can't do that in special relativity …

all frames must have uniform velocity and be non-rotational.

 

[Fredrik]

Tiny-tim, that's not correct. You can use any coordinate system you want as long as you don't call it an inertial frame.

hisham.i, your question doesn't have anything to do with relativity. You have the same issue in Newtonian mechanics. The answer is yes, the kinetic energy is different in different coordinate systems.

 

[tiny-tim]

Hi Fredrik!

Tiny-tim, that's not correct. You can use any coordinate system you want as long as you don't call it an inertial frame.

Yes, I agree, but I meant frames "in special relativity", by which I took hisham.i to mean frames related by the Lorentz transformation.

 

[hisham.i]

hisham.i, your question doesn't have anything to do with relativity. You have the same issue in Newtonian mechanics. The answer is yes, the kinetic energy is different in different coordinate systems.

Yes you are right..
but the point is can i really use this energy in the other reference i mean can i generate electricity from this rotation?

 

[Ikoro]

yes, everything has energy so far it once had a rest mass..or relativistic mass