A metal spoon feels cold when placed in a cup of hot soup because: a) The spoon heats the soup. b) The soup heats the spoon (conduction). c) There is no heat transfer. d) The spoon becomes lighter.>?
The correct answer and explanation is:
The correct answer is b) The soup heats the spoon (conduction).
Explanation:
When you place a metal spoon in a cup of hot soup, the spoon initially feels cold to your touch because of how heat transfer works, especially conduction.
Heat transfer occurs when there is a temperature difference between two objects or substances. Heat naturally flows from the warmer object to the cooler one until thermal equilibrium is reached (both reach the same temperature).
In this case:
- The soup is hot.
- The metal spoon is initially at room temperature, which is cooler than the soup.
The spoon absorbs heat from the soup through conduction. Conduction is the transfer of heat through direct contact between molecules or atoms. The hot soup molecules collide with the molecules in the spoon, transferring energy and increasing the spoon’s temperature.
Metal is a very good conductor of heat, meaning it transfers heat quickly. This is why the spoon’s temperature rises rapidly.
Why does the spoon feel cold initially?
When you first touch the spoon, your hand is warmer than the spoon (because your body temperature is about 37°C, while the spoon is closer to room temperature, say 20–25°C). The spoon feels cold because heat from your hand is rapidly conducted into the cooler metal spoon, making your skin lose heat quickly. This sensation of losing heat is what your nerve endings interpret as “cold.”
As time passes, the spoon heats up from the soup, and eventually, it will feel hot to the touch.
Other options explained:
- a) “The spoon heats the soup” — This is incorrect because the spoon is initially cooler, so it cannot heat the soup; heat flows from hot to cold, not the other way.
- c) “There is no heat transfer” — Incorrect because heat transfer definitely happens via conduction.
- d) “The spoon becomes lighter” — Incorrect, heat transfer does not affect the mass or weight of the spoon.
Summary:
The spoon feels cold initially because it conducts heat away from your hand when you touch it. The soup heats the spoon by conduction, transferring thermal energy from the hot soup to the cooler metal until their temperatures equalize.