A mass $m$ is thrown horizontally on a ice rink with speed $v$. From the point of view of the thrower, the initial kinetic energy is $\frac12 mv^2$. Finally the mass stops a certain distance away thanks to the ice friction. He concludes that the energy dissipated by action of the friction is $\frac12mv^2$.
The same thing is observed from another observer moving opposite to the motion of the mass with speed $v$. The second observer concludes that initially the mass had the kinetic energy $\frac12m(2v)^2 = 2mv^2$ and finally it had the kinetic energy $\frac12mv^2$. Therefore $she$ makes the conclusion that the energy dissipated is $\frac32mv^2$.
Which conclusion is correct? I can assure you at least one is indeed correct.
Can explain the origin, nature, and the size of the difference?
Thank you in advance