volume of the solid of revolution around y axis (1 Viewer)

[Unovan]

Can someone please summarise the steps for finding the volume of the solid of revolution around the y axis? The maths isn't a problem at all, and I'm fine with finding the inverse but what values do I integrate between? Which line do I subtract from the other? etc. etc. It's confusing me for no reason lmao

 

[Unovan]

For the newcastle grammar 2020 trial I lost marks on this question

 

[carrotsss]

You integrate between the min/max y values of the area. You subtract the lower one, as in the one closer to the y axis

hold up I did that question recently in another paper I’ll send my solution

 

[carrotsss]

ignore all the whiteout and stuff I screwed up x^2 at first lmao

 

[howcanibesmarter]

do all farmers have handwriting this bad?

ive seen worse tbf

 

[nsw..wollongong]

do all farmers have handwriting this bad?

its not even that bad i think its just the pen

 

[howcanibesmarter]

speaking of which, can question ask u rotations about a vertical/horizonta line? Like x=5? Cus ive seen some questions like that

 

[mmmmmmmmaaaaaaa]

speaking of which, can question ask u rotations about a vertical/horizonta line? Like x=5? Cus ive seen some questions like that

yeah

 

[howcanibesmarter]

yeah

my teacher said its not part of syllabus, yet a similar question came up in a practice exam, i'm getting mixed answers but thanks theres no harm in learning a little extra

 

[Unovan]

do all farmers have handwriting this bad?

Lmao it's better than mine

 

[yanujw]

my teacher said its not part of syllabus, yet a similar question came up in a practice exam, i'm getting mixed answers but thanks theres no harm in learning a little extra

Looks like you're going to get more mixed answers in this thread. It can't be asked in the new syllabus, it was a part of the old Extension 2 syllabus. That being said, if you understand the visualisation of rotations well enough, it shouldn't be that hard to theoretically imagine how they can be calculated.