- Review the effects of thermal conductivity on thermal energy transfer - Investigate the effects of solid-to-liquid change on thermal energy vs. temperature - Observe the effects of evaporation on temperature TODAY’S OUTCOMES: HEAT Reminder: Course Evaluation Window Is Open until Dec. 7th

10. Julie has noticed that the tile floor in her bathroom feels very cold. She wonders why they don’t use tile to help make picnic coolers. Since you have studied temperature and energy in this course, you can explain. A) Explain the role played by the thermal conductivity of the tile in Julie’s bathroom. Would the floor be less cold if the conductivity were larger or smaller? A larger thermal conductivity makes a room-temperature object feel cooler, because thermal energy from your body will quickly flow away from the touched area. B) Explain the role played by the specific heat of the tile in Julie’s bathroom. Would the floor be less cold if the specific heat were larger or smaller? A larger specific heat (or heat capacity) means more thermal energy is required to raise the tile temperature - so more specific heat (or heat capacity) means the tile will feel cooler. C) Explain how the concept of thermal equilibrium is relevant to why the tiles feel cold. A human body and bathroom tiles are not initially in thermal equilibrium, so heat flows from feet to the bathroom tiles. This makes the tiles feel cold, until thermal equilibrium is reached between the feet and the tile. D) Could you use tile in a picnic cooler to help make things cold? Explain your answer. Tile stored in an ordinary room would not keep things cold in a cooler - in fact, since it’s near room temperature, it would make things worse, as it transfers its thermal energy to the colder cooler.

HEAT CAPACITY ⇔ how much thermal energy a material holds per °C THERMAL CONDUCTIVITY ⇔ how quickly an material transfers thermal energy Qualitative definitions:

TRANSFER OF THERMAL ENERGY - warm material to cold material (equal masses, equal heat capacities): When is the transfer of thermal energy at the highest rate? At the beginning, when the temperature difference is greatest warm material cold material equilibrium temperature What happens to the rate of transfer of thermal energy over time? It gradually slows down. cup of warm water placed in a larger container of cold water, for example

What if the hot object has a higher heat capacity? warm material cold material equilibrium temperature Then the final (equilibrium) temperature goes up! warm material cold material equilibrium temperature (for example, cold water replaced with aluminum)

What if the colder object has a higher heat capacity? equilibrium temperature warm material cold material equilibrium temperature warm object or material cold object or material equilibrium temperature warm object or material cold object or material equilibrium temperature warm material cold material equilibrium temperature Then the final (equilibrium) temperature goes down! (for example, warm water replaced with aluminum)

What if the materials are separated with a good conductor instead of an insulator? equilibrium temperature warm material cold material equilibrium temperature Then the final (equilibrium) temperature would be reached faster. (You saw this when you dropped cold aluminum into warm water!) warm material cold material equilibrium temperature

- How heat capacity and conductivity affect the transfer of thermal energy - How to draw graphs of thermal energy transfer - How heat capacity and conductivity influence these graphs WHAT YOU ARE EXPECTED TO KNOW:

- Review the effects of thermal conductivity on thermal energy transfer ✔ - Investigate the effects of solid-to-liquid change on thermal energy vs. temperature - Observe the effects of evaporation on temperature TODAY’S OUTCOMES: HEAT Reminder: Course Evaluation Window Is Open until Dec. 7th