A metal spoon is left standing in a pot of hot vegetable soup that is at a uniform…
PHYSICS · Multi-part · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter
Problem
A metal spoon is left standing in a pot of hot vegetable soup that is at a uniform temperature of 85 °C. The exposed end of the spoon projects 12 cm above the soup’s surface into air that is at 25 °C.
After several minutes, a student touches both the portion of the spoon just above the surface of the soup and the air directly above that region. The student notices a large temperature difference between the spoon and the air and also observes that the air immediately above the soup feels noticeably warmer than the air farther away.
Answer the following questions about the dominant mechanisms by which thermal energy is transferred in this situation.
(a) Explain which thermal energy-transfer mechanism is primarily responsible for the spoon’s handle becoming hot above the soup’s surface. Justify your answer with reference to molecular interactions and material properties.
(b) Identify and justify the dominant mechanism by which energy is transferred from the soup to the air immediately above its surface.
(c) The student replaces the metal spoon with a wooden spoon of identical dimensions. Predict qualitatively how the dominant energy-transfer mechanism for part (a) would change, if at all, and explain your reasoning.
(d) Suppose the experiment is repeated aboard the International Space Station, where the entire setup is placed in an environment with very little surrounding air. Discuss how the relative importance of the three thermal energy-transfer mechanisms would shift for both the spoon handle and the region just above the soup.