I've been trying to figure out why you can't use the average value of a function to determine the volume of a solid of revolution.(adsbygoogle = window.adsbygoogle || []).push({});

As an example:

Trying to find the volume of a solid of revolution on y=√x from 0 to 1 around the x-axis.

The definite integral is 2/3, which divided by one is still 2/3 so it is the average value.

Then I tried to use turn this into a problem of finding the volume of a solid of revolution around the y=2/3. a radius of 2/3 from 0 to 1. I Since the sides were a straight line I tried to solve for the volume of a cylinder with radius 2/3 and height.

But this didn't work. I've been wracking my brain for like half an hour trying to figure out why but I've got nothing. Can anyone explain to me why this doesn't work?

Thanks in advance.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# I Confusion on the Volumes of Solids of Revolution

Have something to add?

Draft saved
Draft deleted

**Physics Forums | Science Articles, Homework Help, Discussion**