pglpm
@pglpm@lemmy.ca
- Comment on A little physics riddle 4 months ago:
Completely agree, which I think is very interesting. In Newtonian mechanics, some scalar and vector quantities such as mass, internal energy, contact forces (stress), heat flux are frame-indifferent. Other, such as velocity and acceleration, are frame-dependent but we do have transformation rules for them. Some quantities – and quite important ones – such as momentum, are in a sort of limbo: they are frame-dependent, but there’s no clear transformation rule for them.
From the point of view of relativity theory, it’s interesting to note that for this particular case of coordinate transformation – note that it is not a Lorentz boost – we can actually calculate the spatial components of momentum in the new coordinate system, if the reported momentum is expressed as a covariant vector (p_µ). This is because its unknown temporal component (energy) gets multiplied by zero in this transformation. But the text is ambiguous on whether the reported components are covariant or contravariant.
- Comment on A little physics riddle 4 months ago:
Regarding the third body, consider the case where its mass is, say, 2 kg, and the case where it’s 1 kg instead (the momentum being the same).
- Comment on A little physics riddle 4 months ago:
Yes we’re considering Newtonian mechanics in any case. What I’m especially curious about is what physical principles people use to motivate their answers.
- Submitted 4 months ago to physics@mander.xyz | 5 comments
- Submitted 4 months ago to science@mander.xyz | 1 comment