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

When you touch a metal object, it feels colder than a plastic object because of the metal's high thermal conductivity, which allows it to more rapidly transfer energy from your hand, making it feel colder. Meanwhile, the plastic loses heat more slowly due to its lower thermal conductivity, giving the sensation of being warmer. Ultimately, both objects reach the same temperature through heat transfer, but the difference in how quickly they transfer heat creates the contrasting sensations of colder metal and warmer plastic.

Step-by-step solution

Understanding Heat Transfer

Heat transfer is the process of energy exchange between two systems due to a temperature difference. In this case, when your hand touches an object like a piece of metal or plastic, heat energy is transferred between your hand and the object until their temperatures become equal.

Thermal Conductivity

Thermal conductivity is a measure of how well a material can transfer heat. Metals typically have high thermal conductivity, meaning that they can transfer heat more quickly than materials with lower thermal conductivity, such as plastics. In other words, better conductors transfer heat more quickly, whereas insulators take a longer time for heat transfer.

Objects Reaching the Same Temperature

When objects are placed together, they will eventually reach the same temperature through the process of heat transfer. This is a result of energy being exchanged between the objects until their temperature difference is minimized.

The Main Factor

When you touch a metal object, it feels colder than a plastic object because of the metal's high thermal conductivity. The metal's high thermal conductivity permits it to more rapidly transfer energy from your hand to the object. The metal can lose heat more quickly, making it feel colder, while the plastic loses heat more slowly due to its lower thermal conductivity, giving the sensation of being warmer.

Conclusion

The reason a piece of metal feels colder to touch than a piece of plastic in a room, even though they are at the same temperature, is because of the metal's high thermal conductivity. Higher thermal conductivity causes the metal to absorb heat more quickly from your hand, making it feel colder compared to the plastic with a lower thermal conductivity, which takes longer to absorb heat from your hand.