Spoon or No Spoon

Butterflies & Machineguns

While I was drinking my coffee this morning the thought occurred to me: how much faster does my coffee cool with the spoon in it?

So I did a rough estimation with the following assumptions:

  1. All cooling was done through natural convection following Newton’s Law of Cooling, with a convective heat transfer value of h=40 W/(m^2*K) and a bulk air temperature of 294 K (~70 F)
  2. The thermal conductivity of the coffee mug and the spoon are that of ceramic (k=1.5 W/(m*K)) and stainless (k=16 W/(m*K)) respectively
  3. The spoon has uniform temperature along it length equal to that of the bulk coffee
  4. The coffee cup is a cylinder with height of 4 inches and a diameter of 3.5 inches
  5. The spoon has a total length of 8 inches with heat transfer only occurring off the section of the handle emerging from the coffee
  6. Coffee has the same heat capacity and density…

View original post 154 more words

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