All situations take place in an enclosure thermostated at 70°C with air and saturated water vapor. The pressure is constant at p0=1.0×105N m−2.
Physical constants: g=9.8m s−2, μ0=4×10−7H m−1, ε0=8.9×10−12F m−1
Water properties: Density ρ=1.0×103kg⋅m−3, Saturated vapor pressure at 70°C ps=3.1×104N⋅m−2, Surface tension coefficient at 70°C σ=6.5×10−2N⋅m−1, Magnetic susceptibility χ=−9.0×10−6
The gas bubbles that appear during boiling rise to the free surface of the water. Consider that there are only water-saturated vapors in the bubbles and that the radius of a bubble remains constant as it rises. Consider a vapor bubble with a constant radius Rbubble=1.0×10−3m, which rises on the distance h0=1.0×10−1m, with a constant speed vbubble.
E.1. Determine the expression of the mechanical work Lbubble done by the vapor bubble on the water in the vessel, during its lifting. Express the result as function of Rbubble, h0 and vbubble.
E.2. Determine the value of time interval tup, in which the bubble reaches the free surface of the water in the vessel.