Question

On a cold morning, a metal surface on touching is felt colder than a wooden surface because the metal has

• A. Low thermal conductivity
• B. High thermal conductivity
• C. High specific heat
• D. Low specific heat

Hint:

The same principle applies to hot objects. A metal object at 60°C will feel much hotter and cause a burn more quickly than a wooden object at 60°C, because the metal transfers heat *to* your hand much faster. The key concept is the *rate* of heat transfer, which is determined by thermal conductivity.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
This question relates to the concept of heat transfer, specifically thermal conductivity, and how it affects our perception of temperature. Both the metal and wooden surfaces are at the same ambient temperature on a cold morning. The reason they feel different to the touch is due to the rate at which they conduct heat away from our hand.

Step 2: Detailed Explanation:

• Thermal Conductivity: This is a material property that measures its ability to conduct heat. Materials with high thermal conductivity transfer heat quickly, while those with low thermal conductivity (insulators) transfer heat slowly.

• Perception of Cold: When you touch an object that is colder than your body, heat flows from your hand to the object. The sensation of "cold" is not due to the object's temperature alone, but the rate at which your hand loses heat.

• Metal vs. Wood: Metals are excellent conductors of heat, meaning they have a high thermal conductivity. Wood is a poor conductor of heat, or an insulator, meaning it has a low thermal conductivity.

• The Process: When you touch the cold metal surface, it rapidly draws heat away from your hand because of its high thermal conductivity. This fast rate of heat loss makes the nerve endings in your skin register a strong sensation of cold. When you touch the wooden surface, which is at the same temperature, it draws heat away from your hand much more slowly due to its low thermal conductivity. Therefore, it does not feel as cold.

• Specific Heat: Specific heat is the amount of heat required to raise the temperature of a unit mass of a substance by one degree. While it is related to thermal energy storage, it does not directly govern the *rate* of heat transfer upon contact, which is what determines the sensation of coldness.

Step 3: Final Answer:
A metal surface feels colder than a wooden surface at the same temperature because metal has a high thermal conductivity, allowing it to conduct heat away from your hand much faster.