Consider laminar flow of water over a flat plate of length $$1$$ $$m.$$ If the boundary layer thickness at a distance of $$0.25$$ $$m$$ from the leading edge of the plate is $$8$$ $$mm,$$ the boundary layer thickness (in $$mm$$), at a distance of $$0.75$$ $$m,$$ is __________________

Water flows through a $$10$$ $$mm$$ diameter and $$250$$ $$m$$ long smooth pipe at an average velocity of $$0.1$$ $$m/s.$$ The density and the viscosity of water are $$997kg/{m^3}$$ and $$855 \times {10^{ - 6}}$$ $$N.s/{m^2},$$ respectively. Assuming fully-developed flow, the pressure drop (in $$Pa$$) in the pipe is ______________

The difference in pressure (in $$N/{m^2}$$) across an air bubble of diameter $$0.001$$ $$m$$ immersed in water (surface tension $$ = 0.072$$ $$N/m$$) is _____________.

For an incompressible flow field , $$\overrightarrow {V,} $$ which one of the following conditions must be satisfied?