Friday, December 9, 2016

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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