Thermal Energy Transfer: Understanding the Basics

Where does thermal energy always transfer from?

A) warmer; cooler; calories
B) cooler; warmer; joules
C) warmer; cooler; joules
D) cooler; warmer; calories

Answer:

Thermal energy transfers from warmer to cooler objects, with this transfer being measured in joules or calories. The correct choice is C) warmer; cooler; joules.

The question pertains to the transfer of thermal energy, which always transfers from an object of higher temperature to one of lower temperature. The correct statement fills in the blanks as follows: Thermal energy always transfers from warmer to cooler. The transfer of this energy, called heat, is measured in joules, although calories can also be used. Therefore, the correct option is C) warmer; cooler; joules. Notably, the joule is the SI unit of energy, while the calorie is also popularly used, especially in contexts such as food energy content.

According to the second law of thermodynamics, heat transfer flows from a hotter object to a cooler object. Heat changes in chemical reactions are typically measured in joules rather than calories. Understanding that 1 calorie is the amount of heat needed to raise the temperature of 1 gram of water by 1°C is essential when discussing heat flow.