# Volume of a Described Solid

1. Jan 23, 2012

### Jet1045

1. The problem statement, all variables and given/known data
I uploaded of a picture of the question so hopefully it comes up here.

2. Relevant equations

3. The attempt at a solution

OK! so i am SO confused on where to start.
I am imagining the solid flipped on its side with the x axis going through its center.

So all i have is that the integral would be from 0 to h of (pi)(r)^2
Is this at all close?
Any hints would be greatly appreciated. :)

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2. Jan 23, 2012

### Staff: Mentor

That's a start but you have to relate r to h and then integrate over h.

3. Jan 23, 2012

### Dick

r, R and h are given as constants in your diagram. Let's not integrate over any of them. Let y be the distance from the bottom of your solid. So y goes from 0 to h. Then your integral is the integral of (pi)(ρ(y))^2*dy for y from 0 to h. Where ρ(y) is the cross sectional radius of your solid at the height y. ρ(0)=R, ρ(h)=r. Can you figure out an expression for ρ(y) at a general height y?

4. Jan 24, 2012

### Jet1045

I GOT IT !
thanks for the help dick :)