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pentazoid
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Homework Statement
Estimate how long it should take to bring a cup of water to boiling temperature in a typical 600 watt microwave oven, assuming all energy ends up in the water(assume any reasonable initial temperature for the water.) What can you conclude about the amount of heat added to the water?
Homework Equations
P=W/t
possibly Q=W=m*c*delta(T)
The Attempt at a Solution
P=600 watts
W=Q=m*c*delta(T)
c=4.2 J/kg*1
m=.250 grams ( I guessed what the mass of the cup of water would be)
W=(.250)(4.2)(73 K)=76.7 Joules
t=W/P=76.7 joules/600 watts
W/P=t
T_initial=300 K
T_final=373 K
c=4.2
delta(T)=T_final-T_initial=373 K - 300 K= 73 K
not sure if I should just guesstimate the mass of the cup of water.
W=(.250)(4.2)(73 K)=76.7 Joules
t=W/P=76.7 joules/600 watts
Boiling the cup of water in the cup involves work not heat. Energy must be leaving the system(water in this case) to be described as heat. If the cup of water was cooling off, then I could describe that process as heat, not work.