Math Is Fun Forum

Au101

Member

Registered: 2010-12-01

Posts: 353

Integration (Volume of the Solid of Revolution)

Hi guys, I have a question on my integration work, regarding the volume of the solid of revolution.

Does anybody have any ideas? A worked solution can be found online here:

http://mytcl.net/edexcel/c4/c4.html (Go to Chapter 6 (Integration), Exercise L, Question 17) but I can't really follow it properly. Any help would be much appreciated .

Thanks.

Last edited by Au101 (2011-04-05 21:28:09)

gAr

Member

Registered: 2011-01-09

Posts: 3,482

Re: Integration (Volume of the Solid of Revolution)

Hi Au101,

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"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

Au101

Member

Registered: 2010-12-01

Posts: 353

Re: Integration (Volume of the Solid of Revolution)

Thank you, gAr, that's absolutely right. Although, I don't quite see where you get the cone from, I don't suppose you could point that out for me please ?

gAr

Member

Registered: 2011-01-09

Posts: 3,482

Re: Integration (Volume of the Solid of Revolution)

Hi Au101,

You're welcome.
The solid of revolution of a line is a cone, I just wanted to save one integration!
The base radius of the cone is the perpendicular from P, which is a/2.
And height is 5a/4 - 3a/4 = a/2

Meanwhile, I was typing one more way of finding it:

---

"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

Au101

Member

Registered: 2010-12-01

Posts: 353

Re: Integration (Volume of the Solid of Revolution)

Ooooh, thank you very much, that's perfect

gAr

Member

Registered: 2011-01-09

Posts: 3,482

Re: Integration (Volume of the Solid of Revolution)

No problem, You're welcome!

---

"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Integration (Volume of the Solid of Revolution)

Hi Au101;

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.