Question

mary’s stepdad was cooking two identical pot roasts in the oven. her stepdad wrapped one pot roast in foil and left the other one unwrapped. this table shows how the temperature of each pot roast changed over 30 minutes.
pot roast
initial temperature (°c)
final temperature (°c)
pot roast wrapped in foil
30
53
pot roast not wrapped in foil
32
50
the next time mary’s stepdad bakes a pot roast, he wants it to warm up slowly. what should he do to minimize the rate of thermal energy transfer into the pot roast?
wrap the pot roast in foil
leave the pot roast unwrapped
either; the rate of thermal energy transfer is the same whether or not the pot roast is wrapped in foil

Explanation:

Step1: Calculate temp change (foil)

$\Delta T_{\text{foil}} = 53^\circ\text{C} - 30^\circ\text{C} = 23^\circ\text{C}$

Step2: Calculate temp change (no foil)

$\Delta T_{\text{no foil}} = 50^\circ\text{C} - 32^\circ\text{C} = 18^\circ\text{C}$

Step3: Compare energy transfer rates

Foil leads to larger temp increase (faster heat transfer); no foil leads to smaller temp increase (slower heat transfer).

Answer:

leave the pot roast unwrapped