Triet Vo Nguyen Minh

And this is the page: https://physolymp.com/chapters/interference
The setup is at problem 4.

I presume that everybody knows what I'm talking about but just to be sure:
- Meslin's experiment: cut a lens in half and move one half along its principal axis, the intersection of the ray cones is where interference happens.
- by light waves "flipping" I mean a 180° phase change.

I would like to ask a few questions to whoever has been in their national team of competitive physics:
1. Do you receive external pressure, say, from your mentors?
2. How do you keep yourself motivated?
3. Is grinding exercises a correct way to prepare for the Olympiad? In what other ways do you prepare for it?

https://upload.wikimedia.org/wikipedia/commons/1/1f/Special_Relativity.pdf
In the appendix (page 84) of this document, they say $y'=y$ and $z'=z$ because of the relativity postulate.
But I could say $y'=f(v)x + g(v)y$ (2D case) and let f(v) and g(v) be whatever so that the transformation can be inverted if I substitute -v in the brackets.
How would I go about proving that f(v) and g(v) can only be 0 and 1 respectively using the postulates and the assumption of homogeneity and isotropy?

I am currently learning the method of image charges, with the classic point charge, conducting plane example. All is well but when I deal with moving the point charge around, it causes a lot of confusion. I don't know why would the potential of the charge be
-k q / d^2 when it's really close to the plane, with d as the initial distance between plane and charge.

FYI:
The border of the object has no transparency and has an emission shader;
The renderer is Eevee.

Hello? I have a question. How can I resolve this issue? This one is quite well known but most answers doesn't seem to do the trick.
https://imgur.com/a/oT7rFsE

How am I supposed to do something like this with particles, now that Trail Count is deprecated?
https://i1.wp.com/img.talkandroid.com/uploads/2013/09/Sony_Xperia_Z1_Wallpapers_hero_flow_black.jpg

There goes my image.
So even if F_ext = F_max, F_f is still not equal to F_max.