.5 An electric kettle contains 1 kg of water at 20°C. If the thermal capac ity o
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Question
.5 An electric kettle contains 1 kg of water at 20°C. If the thermal capac ity of the kettle itself is equivalent to another 0.5 kg of water, calculat the time required to bring the water to the boiling temperature if the power of the heating element is 2.5 kW. 1.6 The kettle in question 1.5 is accidentally switched on with no water covering the heating element. If the thermal capacity of the element is equivalent to 0.1 kg of water and it is assumed that the element looser no heat from its surface, calculate the time required for the element to reach 500 CExplanation / Answer
Total mass of water Mw = 1 + 0.5 =1.5 kg
Water initialTemperature T1= 20 0C
Boling pointtemperature of water T2=1000C
Heat Transfer Q = m Cp (T2 - T1 )
Cp = specific heat of water = 4200 J/Kg K
Q = 1.5×4200×(100-20)
Q = 1.5×4200×80
Q = 504000 J = 504KJ
Time required to bringwater to boiling point of water t = Heat Tranfer/Power of heating element
t = 504/2.5
t = 201.6 seconds or t =3.36 minutes
As per chegg guide lines I have answered only first Question.
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