@RobinSingh I think you have to treat them as 2 particles it is impossible for them to attain rotational equilibrium, especially the lower one. you can check that by trying to apply torque balance about the point of contact, If you don't have doubt in them being particles and not rigid body then just assume normal and solve force balance for the 2 particles..

@napstablook I think they can still attain rotational equilibrium. Look at the above situation

They haven't given us their radii

the normal still supports the gravity..

in torque I mean.

Yeah you're right

the particle treatment won't yield any determining relation between the masses, I checked

it will only give mu2<mu1

but is it okay to check the torque about point of contact? I mean why not COM

And in what direction would friction act?

kinda rusty on these concepts

@RobinSingh about com you have to take friction into account, we don't know if it is max friction or not so it is kind of difficult

I can't intuitively think of this being a stable equilbrium in case of rigid bodies either way..

For the intuition, can we think of it like we glued the body to the surface

can you tell the source? I doubt this question is correct. but I may be wrong..

It came in a test

did the test paper provide solution?

Here u go

Incomprehensible for me

oh I didn't realize there was friction between the 2, normally I wouldn't consider that but let me check..

Oh yeah you are right

But we don't know if that would be maximum either

hmm you are right but the answer doesn't assume that anyways

I wonder if the normal reaction between the 2 blocks would be greater or less than m2gsin0 ..

I feel like it should be less but I don't understand why..

what this torque balance they used at the beginning justifies is that |f1|=|f2|, I don't think we could use it without sign..

I'm starting to think that the question is not well thought out

I'm usually opposed to think that, but it seems like that, but I think it is worthwhile to wait for JR's opinion.

I hate wrong questions, examiners should respect our hardwork in preperation enough to not make errors in paper and unnecessarily stress us and waste time. :(

In the solution they have assumed equal radii

@napstablook Yeah I agree

@RobinSingh technically they should have stated that too, which test was this? If you don't mind me asking that is.

This was from my coaching

which institute?

Sri Chaitanya

Is their test series worth it? I had been planning to use it but I had no one to tell me their experience..

I think Allen's would be better

We've encountered errors earlier too in these tests

Or Resonance is good too

I enrolled in allen program, I think it is pretty standard set of paper, Usually I have the chance to whine to teachers about errors

I think I will probably not take it, thanks for the opinion

:-)

I can send you one paper of my series if you want to check

@RobinSingh Please do it would be quite a bit of help

also I found out what is wrong in this question wait a sec I am sending

Lol it got uploaded as an image

You have telegram?

@RobinSingh :-))

I do let's talk about that in another chatroom

Sent u an invite

@RobinSingh prnt.sc/1091sr6

@JohnRennie Sir, if free pls help with the two questions

@RobinSingh which two questions?

This and

This

For the second one, I think only A and B are incorrect

OK. I'm answering another question at the moment but I'll look at this as soon as I'm free.

Ok sir

@RobinSingh (a) is certainly incorrect.

(b) is kind of vague. The light intensity certainly does depend on current in an LED.

(c) is technically incorrect as there is always some leakage current in a reverse biased diode due to impurities in the silicon. But the leakage current is usually very small.

(d) I don't know.

@RobinSingh the first question I don't understand at all. Surely it depends on the values of μ₁ and μ₂ ?

Thank you sir :-)

Yes sir the first question is probably wrong

@JohnRennie Hi

How a vector can be resolved into infinite components?

@Wolgwang Do you mean in infinite ways ?

Is there a simple explanation/derivation of why the volume integral of current density over all space is zero in magnetostatics?

this is to basically show that there is no monopole term in the multipole expansion of vector potential but all derivations is find on the web assume a constant line current for some reason. Is there a general derivation for this?

@Rover No