Question

Objects placed together eventually reach the same temperature. When you go into a room and touch a piece of metal in that room, it feels colder than a piece of plastic. Explain.

Short answer

In conclusion, a piece of metal feels colder than a piece of plastic in the same room because metal has higher thermal conductivity and transfers heat from the hand to the metal faster, creating a sensation of coldness.

Step-by-step solution

Understand the concept of heat transfer

When two objects are at different temperatures and come into contact, heat will transfer from the warmer object to the cooler one until both objects reach an equilibrium temperature. In this case, when your hand touches the metal or plastic piece, heat transfers from your hand (at a higher temperature) to the cooler object (the metal or plastic).

Understand thermal conductivity

Thermal conductivity is the property of a material to conduct heat. High thermal conductivity materials can transfer heat more efficiently than low thermal conductivity materials. Metals usually have higher thermal conductivities than plastics, so when your hand is in contact with a metal piece, heat is transferred more quickly from your hand to the metal than to the plastic.

Compare the rate of heat transfer

Since metal has a higher thermal conductivity than plastic, the heat transfer between your hand and the metal piece is faster. This rapid transfer of heat from your hand to the metal makes your hand feel colder when touching the metal compared to the plastic, which transfers heat more slowly.

Perception of temperature

The feeling of cold or warmth when touching objects is actually the perception of heat transfer rather than the object's actual temperature. In this case, both the metal and plastic have reached the same temperature, but the metal feels colder because it transfers heat more rapidly, creating a sensation of coldness on the hand. In conclusion, a piece of metal feels colder than a piece of plastic in the same room because metal has higher thermal conductivity and transfers heat from the hand to the metal faster, creating a sensation of coldness.