AP EAMCET Medical 2017 Shift 1 Paper

Two trains P and Q each of length 400 m are moving along parallel tracks, in the same direction with a same uniform speed of 20 ms−1. Driver of train P decides to overtake train Q and accelerates his train by 1 ms−2. If the train P crosses the trainQ in 50 s. then the initial distance between the two trains was