Runner A begins a sprint along a straight track with an initial speed of 5m/s and accelerates uniformly until his speed becomes 9m/s after covering a distance of 70m. The runner then maintains the same acceleration for an additional 3s.
(i) Calculate the time taken by Runner A to cover the first 70m.
(ii) Determine the magnitude of his acceleration.
(iii) Find the additional distance covered during the next 3s while the same acceleration continues.