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

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 laminar forced convection over a flat plate, if the free stream velocity increases by a factor of $$2,$$ the average heat transfer coefficient

Biot number signifies the ratio of