Two equal point charges (q = +4.50 x 10-6 C) are fixed at opposite corners of a square whose sides have a length of 0.390 meter. A test charge (q0 = -9.50 x 10-8 C), with a mass of 7.90 x 10-8 kilogram, is released from rest at one of the corners of the square. Find the speed of the test charge when it reaches the center of square.