Help with volumes (1 Viewer)

[Aquaz]

How do you know when the slicing or cylindrical shell method requires you to use the big circle minus the small circle formula
for e.g pi(R^2-r^2)

 

[InteGrand]

How do you know when the slicing or cylindrical shell method requires you to use the big circle minus the small circle formula
for e.g pi(R^2-r^2)

This is not usually required for cylindrical shells. Cylindrical shells are generally of the form , where r and h are the radius and height of a cylindrical shell functions of x.

(Further reading may be done here: http://www.stewartcalculus.com/data...texts/upfiles/3c3-Volums-CylinShells_Stu .pdf )

 

[stampede]

Draw a thin slice on the graph and draw in a sketch of what that slice will look like when rotated.

If it looks like it has a hole inside, it'll be like you're asking about "pi(R^2-r^2)"

 

[Aquaz]

Difficult for me to draw/visualise the slice/shell any tips?

 

[braintic]

Difficult for me to draw/visualise the slice/shell any tips?

Watch the demo at the top of this page:

http://mathdemos.org/mathdemos/shellmethod/