Three circular discs of same material and same thickness of radii $r, 2 r$ and $3 r$ are placed on a…
Three circular discs of same material and same thickness of radii $r, 2 r$ and $3 r$ are placed on a horizontal plane such that their centres lie along a straight line. The radius of the middle disc is $2 \mathrm{r}$ and it touches the other two discs. The distance of the centre of mass of the system from the centre of the smaller disc is ________ .