Using the boundary layer velocity theory:

Along a flat plate $1\mathrm{.}2$ m in length, water flows with an approach velocity of $0\mathrm{.}5$ m$/$s$.$ It is required to determine the distance $"$y$"$ from the surface of the plate at which the water velocity is $0\mathrm{.}3645$ m$/$s at a position located at x$=40$ cm from the leading edge.