Need help with finding a volume of revolution with Cylindrical Shells method

y=2-0.5x, y=0, x=1, x=2, rotate about the x axis.

I know that it will be easier to solve it with the regular method, but I need it with cylindrical shell.

I cannot find the radius and the height.

The final answer is 19pi/12

Thanx

Re: Need help with finding a volume of revolution with Cylindrical Shells method

Quote:

Originally Posted by

**shaharg** y=2-0.5x, y=0, x=1, x=2, rotate about the x axis.

I know that it will be easier to solve it with the regular method, but I need it with cylindrical shell.

I cannot find the radius and the height.

If you must use the shell method, you will need to set up two integrals: one for in which the height of each shell is simply 1, and then another for in which the height of each shell is

Re: Need help with finding a volume of revolution with Cylindrical Shells method

Quote:

Originally Posted by

**Reckoner** If you must use the shell method, you will need to set up two integrals: one for

in which the height of each shell is simply 1, and then another for

in which the height of each shell is

So, what is the radius and what is the height?

Re: Need help with finding a volume of revolution with Cylindrical Shells method

Quote:

Originally Posted by

**shaharg** So, what is the radius and what is the height?

I suggest drawing a picture. The average radius of each shell is the distance from the axis of rotation to each given -value. Since the axis of rotation is simply the -axis, this distance is given by The "height" of each shell (horizontal distance from side to side) I have explained in my previous post. It should be clear from looking at a picture.

Re: Need help with finding a volume of revolution with Cylindrical Shells method