Metric system energy measurement

Nutritional energy values are usually measured in kilocalories (kcal or simply calories). One kilocalorie represents the amount of heat required to raise the temperature of 1 kg of water by 1°C at room temperature. In the metric system, the energy value is expressed in joules (J), with 1 kcal being equal to 4.184 kilojoules (kJ). 

The metric system consists of a base unit and (sometimes) a prefix multiplier. Most scientists and healthcare providers use the metric system, and you are probably familiar with the common base units and prefix multipliers. The base units describe the type of quantity measured length, mass, or time. The SI system is sometimes called the MKS (meter, kilogram, second) system, because these are the standard units of length, mass, and time upon which derived quantities, such as energy, pressure, and force, are based. An older system is called the CGS (centimeter, gram, second) system. The derived CGS units are becoming extinct. Therefore, we will focus on the MKS units. 

The measures of length, volume, mass, energy, and temperature are used to evaluate our physical and chemical environment. Table 2.2 compares the metric system with the more recently accepted SI system (International System of Units). The laboratory equipment associated with obtaining these measures is also listed. 

In the metric system the calorie is defined as the amount of energy (heat) required to raise the temperature of one gram of water by one Celsius degree. The "calorie" with which you are probably familiar is used to measure the energy content of food and is actually a kilocalorie (1000 calories), written with a capital C (Calorie) to distinguish it from the calorie used in chemistry. The joule (an SI unit) can be most conveniently defined in terms of the calorie ... 

JOULE - The unit used to measure heat, work, and energy in the metric system. Its symbol is J. It is the amount of energy required to move an object of 1 kg mass to a height of 1 m. Also called a newton-metre. 

In this chapter, I cover the two basic components of the universe — matter and energy. I examine the different states of matter and what happens when matter goes from one state to another. I show you how the metric system is used to make matter and energy measurements, and I examine the different types of energy and see how energy is measured. 

Understanding the states of matter Differentiating between pure substances and mixtures Measuring matter with the metric system Examining the properties of chemical substances Discovering the different types of energy... 

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