1. The problem statement, all variables and given/known data Here is the question: Thin rod AB has length l=100 cm and total charge q=37 nC that is distributed in such a way that its line density ? is proportional to the square of the distance from the end A, i.e. ?(x) =kx^2. Determine electric field E at the end A of the rod. ? stands for Lambda, sorry I do not understand TeX. I know that I need to integrate SOMETHING. How I do that I am not sure. Here are a couple of questions: 2. Relevant equations - Can I assume that at 1m: (37nC)/1m=k(1^2) to find k? (or is k just 8.97E9?) - Do I use the formula E=lambda/((2)(pi)(epsilson-nought)(x)) because this is a cylinder? 3. The attempt at a solution This is what I have so far: solve for k at 1m and see that it equals 37 nC (should I just convert that to C?) input lambda into the equation and do an integral so you get: k(x^2)/((2)(pi)(epsilon-nought)(x)) from A (0) to B (1 m). From this I got that the integral is k(x^2)/((4)(pi)(epsilon-nought)). This is where would end the problem and put in my values. I really just want to understand the problem, obviously there is something I am not getting. Thanks in advance. PS I know there is this exact question (I did my research on this problem before I came here). I didn't understand the explanation there so please help!