Four charged balls are placed and held at the corners of a square with side lengths of 1.0 m. The charges of the balls are as follows, upper left 5.0x10- C. Upper Right -3.0x10- C. Lower Right 6.0x10- C, and Lower Left -2.0x10-6 C. a. Find the net force (magnitude and direction) acting on the lower two balls. (8 marks) b. If the Lower Right charged ball were released what would be its initial acceleration if its mass were 3.0 kg? (2 marks)