The Physics
Opus in profectus

Sensible Heat

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  1. An 850 W consumer coffee maker can make 10 cups (1.75 liters) of 80 °C coffee from 20 °C tapwater in 10 minutes. What percentage of the electric energy consumed actually makes it to the coffee?
  2. A 100 g cube of aluminum is removed from a bath of boiling water and dropped in a bath of room temperature water (2.00 liters at 20.0 °C). What is the final temperature of the water and zinc assuming heat loss to the surroundings is negligible?
  3. Write something different.
  4. Write something completely different.


  1. An ordinary thermometer consits of 25 g of glass and 2 g of ethyl alcohol. If it has an initial temperature of 22 °C, what temperature will it read when it is completely submerged in 100 g of 80 °C water?
  2. Large chicken egg on an electronic balance reading 65.9 grams
    Large chicken egg (65.9 g)
    A perfectly cooked egg in the shell should reach a final temperature of 63 °C. If you don't have access to an immersion heater (a.k.a. a sous vide) it should be placed in boiling hot water, but not in boiling water. Once the cooking water starts boiling, the heat should be turned off, the egg submerged, and the pot covered. When both the cooking water and the egg are at 63 °C it is ready to eat. Determine the minimum mass of water needed to accomplish this task if…
    1. the egg was removed from a refrigerator at 4 °C and cooked in New York City where the boiling point of water is 100 °C
    2. the egg was removed from a pantry at 22 °C and cooked in the south of France where the boiling point of water is 100 °C
    3. the egg was removed from a hen house at 15 °C and cooked in the Himalayas where the boiling point of water is 82 °C