In the figure is a rectangle ABCD with sides AB = 6, BC = 8. Suppose a dynamic point P starts to move along AC from point A to C at speed of 2 units/second. In the mean time, another dynamic point Q starts to move along CB from point C to B at speed of 1 unit/second. The motion will end when either of them reach the terminal. Find the time of t when \triangle PQC is an isosceles triangle during the moving of point P and Q.
