shit things for exam (1 Viewer)

[hup]

are these necessary

pencil for diagram
compass ruler for circles and graphs

what proof for cylindrical shells?
do you have to do the whole r +dx etc and neglect dx^2
or can you just draw the rectangle thing and show V = 2pirh dx

i will add more if i come across

 

[artosis]

i wanna know about the compass thing too.

if u look at the bos sample answers for the 2009 ext 2 paper, they didnt use a compass :S

 

[Official]

are these necessary

pencil for diagram
compass ruler for circles and graphs

what proof for cylindrical shells?
do you have to do the whole r +dx etc and neglect dx^2
or can you just draw the rectangle thing and show V = 2pirh dx

i will add more if i come across

For cylindrical shell I might do the whole r+dx, etc, especially if it is a 4 marker, it's too risky not to imo

 

[blackops23]

do you have to do the whole r +dx etc and neglect dx^2

.... what is the point of making one of the most simplest things in 4U (a formula that is only 2pirh) into a complicated thing? I don't think I've ever learnt r+dx but im guessing it takes into the width of the thickness of the cylinder?

AWARE me if i'm wrong, but i thought in 4 u they didnt take marks off for insufficient working - and that only occurred in 2u, and to a lesser extent in 3u

 

[timting95]

For the cylindrical shells i would include it, it doesn't take much time extra maybe 5 more seconds?? But if you have a look at the MX2 syllabus it actually says that you need to be able to come to V = 2pirh etc... So i'd say do it, unless you don't know how to - then don't do it

 

[Riproot]

For the cylindrical shells i would include it, it doesn't take much time extra maybe 5 more seconds?? But if you have a look at the MX2 syllabus it actually says that you need to be able to come to V = 2pirh etc... So i'd say do it, unless you don't know how to - then don't do it

Yeah, I have no idea what you're talking about...

 

[AAEldar]

In the MANSW past paper + solution books they include the sum and exclusion of and all that in their answers and my teacher/head teacher have both advised us to include it.

Pencil for diagram? No thank you!

 

[Omnipotence]

what is the point of making one of the most simplest things in 4U (a formula that is only 2pirh) into a complicated thing? I don't think I've ever learnt r+dx but im guessing it takes into the width of the thickness of the cylinder?

AWARE me if i'm wrong, but i thought in 4 u they didnt take marks off for insufficient working - and that only occurred in 2u, and to a lesser extent in 3u

LOL I've always did it r + dx

 

[Riproot]

LOL I've always did it r + dx

Wtf is r+dx?
Someone please awares me!

 

[D94]

oh fuck that shit.... what is the point of making one of the most simplest things in 4U (a formula that is only 2pirh) into a complicated thing? I don't think I've ever learnt r+dx but im guessing it takes into the width of the thickness of the cylinder?

AWARE me if i'm wrong, but i thought in 4 u they didnt take marks off for insufficient working - and that only occurred in 2u, and to a lesser extent in 3u

The 2(pi)xy or 2(pi)rh method skips steps which are evident in the setup for the r + dx or x+ dx method. Essentially, the r + dx method leads onto a 2(pi)rh method.

Wtf is r+dx?
Someone please awares me!

You take a cylindrical shell with larger radius as x + dx and then a smaller radius as x and then you apply the volume of a cylinder formula. So you get:



Then you substitute in the height () and integrate it.




It's the same thing, but the setup which I just showed 'could' be worth a mark.

 

[Official]

The 2(pi)xy or 2(pi)rh method skips steps which are evident in the setup for the r + dx or x+ dx method. Essentially, the r + dx method leads onto a 2(pi)rh method.



You take a cylindrical shell with larger radius as x + dx and then a smaller radius as x and then you apply the volume of a cylinder formula. So you get:



Then you substitute in the height () and integrate it.




It's the same thing, but the setup which I just showed 'could' be worth a mark.

<3

 

[Riproot]

You take a cylindrical shell with larger radius as x + dx and then a smaller radius as x and then you apply the volume of a cylinder formula. So you get:



Then you substitute in the height () and integrate it.




It's the same thing, but the setup which I just showed 'could' be worth a mark.

My teacher never mentioned that.
I'm such a stressball right now.