PHY（功率）急～～

Heat needed to raise the temperature of 5 kg of water from 25'C to 100'C
= 5 x 4200 x (100-25) J = 1 575 000 J
where 4200 J/kg-C is the specific heat capacity of water

Heat required to vapourize 2 kg of water
= 2 x 2 260 000 J = 4 520 000 J
where 2,260,000 J/kg is the latent heat of vapourization of water

Hence, total amount of heat supplied by the oven
= (1575 000 + 4520 000) J = 6 095 000 J
Therefore, power of oven = 6 095 000/(3x60) J/s = 33 861 w = 34 kw

2011-01-02 10:28:36 補充：
molecules in gas state are completely free from intermolecular force, whereas molecules in liquid state are still bound by intermolecular force and only have limited translational motion.

1)First:
功率的公式=P=E/t
因為水的比熱容量是4200....
SO,
c=E/m(T2-T1)
4200=E/5X75
E=1575000J
P=E/t
P=1575000/3X60
P=8750W
so,
功率是8750W