A charge of 2.75 μC is held fixed at the origin. A second charge of 2.75 μC is released from rest at the position (1.15 m, 0.350 m). If the mass of the second charge is 1.50 g, and its speed when it moves infinitely far from the origin is 8.6838 m/s, at what distance from the origin does the 2.75 μC charge attain half the speed it will have at infinity?(adsbygoogle = window.adsbygoogle || []).push({});

I calculated the 8.6838 m/s by using PEi = KEf +. kq1q2/r = (mv^2)/2 => v = sqaure root of (2kq1q2/mr). I tried rearranging the equation to solve for r = 2kq1q2/mv^2, and got an answer of 4.8084 m, however, my answer is not correct. I used k = 8.99 x 10^9 Nm^2/C^2, q1 = 2.75 x 10^-6 C, q2 = 2.75 x 10^-6 C, m = 0.0015 kg, and r (for the first problem) = 1.2021 m (using Pythagorean theorem). Any ideas of where I went wrong?

**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!

# Homework Help: Charge at origin

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