A ring and a disc are initially at rest, side by side, at the top of an inclined plane which makes an  angle 60° with the horizontal. They start to roll without slipping at the same instant of time along the shortest path. If the time difference between their reaching the ground is 2−3/10s , then the height of the top of the inclined plane, in meters, is  ____________.Take g=10m/s2.