Why is the end area of shell [tex]2\pi rdr[/tex]?
Thanks in advance.
It's the area expressed in differential form. To acquire the correct formula, you need to calculate the integral with respect to r.
Intuitively, the differential form means this : to describe an infinitesimal small area, take the circumference 2 times pi times r and make it a bit thicker, expressed by the dr. Integrating over r means that you sum up the area of all this different, very thin, circumferences to get the total circular area.
Oh, I got that! Thank you marlon! I am giving my first steps over integration. And congratulations for the award!!
What award ?
I just lost my guru badge to somebody else, lol.
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