Physics Question - Electric Food Steamer?
An electric steamer works in the following way. Add water to the lower compartment, and the steamer changes water to steam. The steam rises through the holes in the base of the food compartment and the food will be steamed.
Broccoli and fish needs 600 kJ to be steamed. The power rating of the steamer is 800 W and specific latent heat of vaporisation is 2.3 x 10^6 J/kg.
a) Calculate the time required for steam the broccoli and fish after the water has reached 100°C.
b) Calculate the mass of water that has been converted to steam during this period of time.
c) Do you think the food will cook faster if it is placed in boiling water instead of using the steaming method? Explain.
d) John commented that the part of the fish near the bottom of the food compartment might be over cooked while the upper part might not be cooked enough. What would you say to him?
Thanks in advance.
a)
1 W = 1 J/s , 600 kJ = 600000 J
The time required = 600000 J / 800 (J / s) = 750 s = 12.5 mins
b)
The mass of water = 600000 J / 2300000 (J/kg) = 0.261 kg
c)
The food will cook slower if it is placed in boiling wate, because the heat transfer rate is better in steamer than in boiling water.
As the steam is condensed, more heat is released due to the latent heat.
d)
It depends on the design of the steamer.
Usually it is thermal homogeneous in a steaming steamer.
Electric Body Electric Food (Dr. Sebi, Jewel Pookrum, Mildred Nelson)
