If E=mc^2, how does it relate to Ek+1/2 mv^2?

Question

How does it work when v = c?

thanks

Answer 1

I don't know what your question is exactly

E=mc^2 can mean two things:
a) the energy equivalent of a rest mass, or
b) the energy equivalent of a mass exchange for energy. Energy is mass, and mass is energy. That is what we call mass equivalency.
On the Ek=1/2 mv^2, that does not work of for v approaching the speed of light, relativity takes over, and mass itself changes as speed of light is approached.

Answer 2

Thank you