As shown in the figure, eight identical point charges with charge q are fixedly mounted on a (non- conductive) circle with a radius r = 60 cm. In the center of the circle, there is a corresponding negative point charge fixedly mounted. a) At time t = 0, the bottom charge on the circle breaks free and moves with a constant velocity v1 in the downward direction, along the x-axis in the depicted coordinate system. The velocity is v1 = c/3. What is the total force vector on the charge (-a) in the middle of the circle two nanoseconds later, i.e.. at time t = 2 ns? Express the answer in units of F0 = q2/(4\pi \epsi or^2). What is the answer if t = 3 ns? It can be assumed that the other charges do not move. b) Same question as in a), i.e., the force on the charge (-a) in the middle of the circle after 2 and 3 nanoseconds, but now with velocity v2 to the left, along the y-axis in the depicted coordinate system. Here also, the velocity is v2 = c/3. +9 b+ +q V b+ b+ ******* r -q V1 b+ b+ b+ y