Question

Compare the energy required to evaporate a kilogram of water at 15 celsius to that required to raise it 3 km into the air (1kg on earth weighs 9.8 N, and 1 J=1 N-m)

Answer 1

FOR evaporating water :
specific heat capacity of water, C = 4.186 J/goC
latent heat of vaporization of water LV = 2264.76 J/g
m = 1 Kg = 1000 g

Total energy = energy to take water from 15 oC to 100 oC + Energy to evaporate water at 100 oC
    = m*C*delta T + m*Lv
    = 1000*4.186* (100-15) + 1000*2264.76
     = 355810 + 2264760
     = 2620570 J

For raising water:
m = 1 Kg
weight = 9.8 N
h = 3 Km = 3000 m

energy = weight * height
     =9.8*3000
     =29400 J

Energy required to evaporate water is larger by
2620570 / 29400 = 89 times