Cylindrical shells (parts in details)?
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#f(x)=x^2# , #y=0# , #x=1#
Set up a volume (shell) derivative based on the following axes of rotation:
(A) around #x=-2#
(B) around #x=2#
(C) around #y=-2#
(D) around #y=2#
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Can you use washers for (A) and (B) in the previous question? Why or why not?
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"Pikachu claims that no matter what kind of problem, you can always use disks/washers and shells. Is this true? Explain."
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#f(x)=x^2# ,#y=0# ,#x=1#
Set up a volume (shell) derivative based on the following axes of rotation:
(A) around#x=-2#
(B) around#x=2#
(C) around#y=-2#
(D) around#y=2# -
Can you use washers for (A) and (B) in the previous question? Why or why not?
-
"Pikachu claims that no matter what kind of problem, you can always use disks/washers and shells. Is this true? Explain."
2 Answers
I have some parts of this question answered; feel free to check/change where needed
Explanation:
Here are my answers for number 1
(A)
(B)
(C)
(D)
For attempted answers to questions 2 and 3. please see below.
Explanation:
- (A)
Shells:#V = 2piint_0^1 (x+2)x^2 dx = (11pi)/6#
Washers:
(B)
Shells:
Washers:
3.
Obviously Pikachu is not correct. You cannot use discs/washers or shells to solve a related rates problem.
In theory, for any solid of revolution, we can use either. But consider the following problem.
Find the volume that results if the region bounded by the curve
graph{xsinx [-1.456, 4.702, -0.76, 2.318]}
Using shells, this is
To use washers we need expressions for the
Since
So we could do it using washers (maybe), but we sure wouldn't want to.