26.A train runs past a telegraph pole in 15 second, and through a tunnel 450 metre long in 45 s. The length of the train is

27.A ball falls freely from rest . The ratio of the distances traveled in first, second, third and fourth second is

28.Two different masses m and 2m are fallen from height H1 and H2 respectively. First mass takes t second and another takes 2t second, then the ratio of H1 and H2 is:

29.A steam boat goes across a lake and comes back (i) on a quiet day when the water is still and (ii) on a rough day when there is a uniform current so as to help the journey onwards and to impede the journey back . If the speed of the launch on both days was same, the time required for complete journey on the rough day, as compared to the quiet day will be