1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 4 Lecture Outline Prepared by Jennifer N. Robertson-Honecker West Virginia University

2 Energy Energy is the capacity to do work. Potential energy is stored energy. Kinetic energy is the energy of motion. The law of conservation of energy states that the total energy in a system does not change. Energy cannot be created or destroyed.

3 Energy The Units of Energy A calorie (cal) is the amount of energy needed to raise the temperature of 1 g of water by 1 o C. A joule (J) is another unit of energy. 1 cal = J Both joules and calories can be reported in the larger units kilojoules (kJ) and kilocalories (kcal). 1,000 J = 1 kJ1,000 cal = 1 kcal 1 kcal = kJ

4 Cal/gcal/g Protein44,000 Carbohydrate44,000 Fat99,000 Focus on The Human Body Energy and Nutrition The amount of stored energy in food is measured using nutritional Calories (upper case C), where 1 Cal = 1,000 cal. Upon metabolism, proteins, carbohydrates, and fat each release a predictable amount of energy, the caloric value of the substance.

The Three States of Matter