A 3-4-5 inclined plane with inclination $\theta =={\sin }^{-1}\frac{3}{5}$  is fixed to a rotating turn table as shown in figure. A block rests on the inclined plane and the co-efficient of static friction between the inclined plane and the block is ${\mu }_s=1/4$ . The block is to remain at a position 40 cm from the axes of the turn table. Then the minimum angular speed of turn table required to keep the block from sliding down the plane  $(g=9.8m/s^2)$