If $$'P'$$ is the gauge pressure within a spherical droplet, then gauge pressure within a bubble of the same fluid and of same size will be:

Kinematic viscosity of air at $${20^0}C$$ is given to be $$1.6 \times {10^{ - 5}}\,\,\,{m^2}s.$$ Its kinematic viscosity at $${70^0}C$$ will be varying approximately :

Water flows through a vertical contraction from a pipe of diameter $$d$$ to another of diameter $$d/2$$ (see Figure). The flow velocity at the inlet to the contraction is $$2m/s$$ and pressure $$200$$ $$kN/{m^2}.$$ If the height of the contraction measures $$2m$$, then pressure at the exit of the contraction will be very nearly

It is proposed to coat a $$1mm$$ diameter wire with enamel paint $$\left( {k\,\,\,\, = 0.1W/m} \right.$$ - $$\left. K \right)$$ to increase heat transfer with air. If the air side heat transfer co-efficiency is $$100$$ $$W/{m^2}K,$$ the optimum thickness of enamel paint should be