a block of mass m is placed on a smooth turntable at a distance of 20cm from the centre.a string is tied to the block and its other end passed through a gole in the centre of the table.A 2nd block of mass m is suspended from the free end of the string as shown in fig.At what angular speed should turntable rotate so that the block placed on it should remain at rest on its surface?

1 answer

tension max=mg from the hanging mass

centripetla force=mw^2*r

tensionmax=mr*w^2
mg=mr*w^2
w=sqrt(g/r) radians per second.