Converting to Polar Coordinates

[jenn9580]

I am looking for the total charge on a disk, radius 2, with a charge density at (x,y) is ?(x, y) = 5x + 5y + 5x^2 + 5y^2. I know I need to convert to polar & use the double integral. x^2 +y^2 will become r^2, but what happens to the 5x+5y? Do they become rcos & rsin?

 

[tkhunny]

You have it. Why do you doubt?

 

[jenn9580]

I ended up with an answer of 40pi & I thought that would be an incorrect answer, in coulombs. My professor believes in "conceptual knowledge" & that we should self-teach, so I wasn't sure. Thanks!!