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04:00 - 15:0015:00 - 20:00

John Rennie
John Rennie
15:01
@Abcd to be honest I wish I'd just drawn a diagram like the one above for that question.
Isn't it obvious from the diagram why the reading is 28.3? No messing around with MSDs or whatever.
Abcd
Abcd
nope its not obvious to me
@JohnRennie why move left??
John Rennie
John Rennie
@Abcd If you start with the calipers closed then the zero on the main scale and the zero on the vernier scale are aligned. Yes?
Abcd
Abcd
@JohnRennie yes
John Rennie
John Rennie
Now you put some object with a size $D$ in the jaws. That means the movable jaw has to move a distance $D$ to the right.
The vernier scale is written on the movable jaw, so that means the whole vernier scale moves a distance $D$ to the right along with the movable jaw.
OK so far?
Abcd
Abcd
@JohnRennie yeah
John Rennie
John Rennie
15:10
So the zero on the vernier scale is now at a distance $D$ on the main scale.
user image
Abcd
Abcd
@JohnRennie agree
John Rennie
John Rennie
We can see that $D > 28$ and $D < 29$ but we can't be any more precise than that because the main scale is only marked in 1 mm steps.
But we know that 7 on the vernier scale lines up with 36 on the main scale.
Abcd
Abcd
@JohnRennie ya
John Rennie
John Rennie
And we know the vernier spacing is 1.1mm
So that means $D + 7.7 = 36$
Abcd
Abcd
@JohnRennie Wow!!
John Rennie
John Rennie
15:15
@Abcd Yes :-)
It really is as simple as that!
Abcd
Abcd
Why do people like to complicate stuff
John Rennie
John Rennie
@Abcd now you see why I wish I had drawn this diagram earlier. I just didn't think of doing it.
PolarBear
PolarBear
If the limiting value of $\mu$ friction coefficient for a block to topple and slide is same, what will happen first, tippling or sliding?
John Rennie
John Rennie
@PolarBear call the limiting value $\mu_0$. Now if you have $\mu > \mu_0$ the block topples. If you start with large $\mu$ and then see what happens as you reduce $\mu$ the block always topples.
If you have $\mu < \mu_0$ the block slides. So start with small $\mu$ and increase it towards $\mu_0$ and the block always slides.
So what happens at $\mu_0$ depends on which direction you approach from. That means the behaviour at $\mu_0$ is not defined.
PolarBear
PolarBear
@JohnRennie Ahha, I get it. In the question it's the former case. But why?
John Rennie
John Rennie
15:25
@PolarBear I'd have to see the question
PolarBear
PolarBear
Oh wait, got it.
What you said is correct
The question's a bit long though and the question finally boils down to what I asked
I missed that the question said it was always greater than $\mu_0$
Thank you for pointing it out because I forgot.
Abcd
Abcd
16:08
@JohnRennie Can you please explain what does $\dfrac{dN u}{N du}$ exactly mean in Maxwell's distribution curve
@JohnRennie Are you there?
@AdvilSell ^^^^
Advil Sell
Advil Sell
@Abcd ah..I can't explain it ! sorry
Abcd
Abcd
@AdvilSell do you know what it is??
Advil Sell
Advil Sell
@Abcd Sorta , But surely I can't explain it
Abcd
Abcd
@AdvilSell k
John Rennie
John Rennie
16:31
@Abcd Maxwell distribution?
Abcd
Abcd
@JohnRennie chem.libretexts.org/Bookshelves/…
Advil Sell
Advil Sell
@JohnRennie Maxwell-Boltzmann distribution
Abcd
Abcd
@JohnRennie instead of probability on Y axis my book has dNu/Ndu
John Rennie
John Rennie
@Abcd can you post a picture?
Abcd
Abcd
@JohnRennie yes
user image
John Rennie
John Rennie
16:40
@Abcd I have to admit I don't understand what that means.
Abcd
Abcd
@JohnRennie Okay
Dante
Dante
@Abcd Given briefly in Opt about the deferential expression.
 
2 hours later…
amanuel2
amanuel2
19:07
Physics exam tommorow :(
Advil Sell
Advil Sell
@amanuel2 All the best man :D
amanuel2
amanuel2
Thanks :)
About to review a lot so I might ask some question to the physics whiz's @tatan and @JohnRennie ;)
04:00 - 15:0015:00 - 20:00

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