Recent content by loup

I cannot use parallel axis theorem. I think it is too tricky.

The r requires a cosine and there are more than one variable, what I should do?

And I think the integration of disc actually comes from cylinder. I expected once I finished this cylinder I could do the disc.

The problem is I don't know about how to integrate a disc.

When I am reading a book, I find it is listed that the moment of Inertia of a cylinder is MR^2/4 + Ml^2/12 It is a cylinder with rotation axis passing through the curve surface and its centre of mass. And its density is constant. With the circile surface raius = R and height = l Can...

I know spin = 1/2 meaning that the particle rotates 720 degree than looks the same as the original one. But, -1/2, what does that imply? j and m? What do they mean?

Why there can exist some particles having spin = 1/2? I understand, the postive numbers but what do the negative number mean? Also, I would like to ask why some photons can be detected when it comes to light, but photon is not detected when it comes to charge replusion? What is the difference...

Yes, I saw that. Anyway, thanks for your help really. I will study all the posts you have posted seriously.

That means I have not fully understood what you have said... It seems that I have to try harder

It must be the most difficult integration so far I have encountered. But at the same time, it fasinates me. What is the next step, arildno?

What about my questions? Proof for sound effect I clearly understand. But light cannot be treated as relative velocity, it is absolute, isn't it?

I group what Arildno's for a clearer overview

How to prove the doppler effect for light wave? Isn't that the speed of light is constant for both the observer and source? If the wavelength for both the source and observer is the same, then the frequency is the same too, so there is no doppler effect? If the wavelength is different...

aridno, I agree with what you say. Thank you very much.

But if P is inside the ball. Isn't that not only the things nearer than P to the centre contributes to the gravity, but also the things outside P? I know the things outside P will cancel each other, but how to prove the things outside P will cancel each other ?