The power of the hair dryer is 1500W. It is estimated that the air at room temperature ( 25
degree celsius ) enters the hair dryer at a rate of 0.045 kg s ^-1 and leaves the barrel at
50 degree celsius.
1. Calculate increase of internal energy of the air in 1 s.
given: specific heat capacity of
air = 1000 J kg^ -1 degree celcius ^-1
2. Some energy is wasted in the process. State TWO different ways by which energy is
wasted.
S4 Physics calculation
2009-10-08 2:40 am
回答 (1)
2009-10-08 2:49 am
✔ 最佳答案
1. Increase of internal energy in 1 s= mcT / t
= (m/t)cT
= 0.045(1000)(50 - 25)
= 1125 J
2. See that the increase in internal energy of the air is less than the energy supplied by the hair-dryer in 1 s.
Some energy is wasted in the process.
Energy is lost as sound energy of the dryer.
Also, energy is lost to increase the internal energy of the dryer.
參考: Physics king
收錄日期: 2021-04-19 15:55:47
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