Chapter 17, Problem 49A

Interpretation Introduction

Interpretation: The sign convention used when describing heat flow in a system is to be described.

Concept Introduction: Heat is the form of energy that is transferred between bodies or objects at two different temperatures.

Heat is always transferred from the object at the higher temperature to the object at the lower temperature.

Answer to Problem 49A

The sign convention for heat is positive when it flows into the system and the sign convention for heat is negative when it flows out of the system.

Explanation of Solution

Heat is represented by the symbol and units of Joule. is chosen to be positive when heat flows into the system and negative when heat flows out of the system. Heat flow is a result of a temperature difference between two bodies, and the flow of heat is zero if both bodies are at the same temperature.