I wanted to make a quick dinner last night so that I could
get back to studying, so I decided to make pasta. Wanting to multitask, I did
some dishes while the pasta was cooking in the boiling water. When I was done
with the dishes I stirred the pasta with the fork that I had left in the pot.
I forgot that the fork would probably be hot since I had left it
in the boiling water.
By the time I touched the fork after
leaving it in the boiling water, its temperature would have
been:
Q = mcΔT
The heat required to warm up an iron pot to 100 °C from room temperature is:
Qpot = 1 kg * 450 J/kg°C * (100 °C - 20 °C) = 36000 J
The heat required to take the water from room temperature to boiling is:
Qboilingwater= 0.25 kg * 4186 J/kg°C * (100 °C - 20 °C) = 83720 J
Qpot + Qboiling water = 119,720 J
The temperature change in an aluminum spoon from room temperature assuming that this is a closed system:
Q = mcΔT
119,720 J = 0.3 kg * 900 J/kg°C * (Tf - 20 °C)
Tf = 443 °C
This would have been hot enough to burn my hand. Luckily it was not a closed system and a lot of heat was lost to the air and I was able to go back to making notes pain-free.
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