1. The problem statement, all variables and given/known data What are the strength and direction of the electric field at the position indicated by the dot in the figure? Answer in component form. 2. Relevant equations E=kQ/r^2 3. The attempt at a solution E(+5) = (8.99E9)(5E-9)/(0.02^2) = (1.1E5i, 0j) E(-5) = (8.99E9)(5E-9)/(0.02^2) = (0i, 2.8E4j) r(+10) = SQR(0.02^2+0.04^2) = 0.0447 E(+10) = (8.99E9)(10E-9)/(0.0447^2) = 4.5E4 arctan(2/4)=26.57DEG = (4.5E4sin(26.57)i, 4.5cos(26.57)j) = (2.0E4i, -4.0E4j) E(+5) + E(-5) + E(10) = (1.3E5i, -1.2E4j) Mastering Physics is telling me that this answer is wrong and I want to know where I screwed up.
The problem may well be too much round-off error. Keep at least two extra digits for all intermediate results. Round-off your final result to the correct sig. dig. if whoever/whatever is grading your work is anal about such things.
Turns out it was the comma in my vector notation. Once I removed the comma, the computer accepted it. Looks like I'm a bit rusty on that stuff. Thank you both for your help.