A particular frost-free refrigerator uses about 745 kWh of electrical energy per year. Express this amount of energy in each unit. a. J b. kJ

Verified step by step guidance

1. Step 1: Understand the relationship between kilowatt-hours (kWh) and joules (J). 1 kWh is equivalent to 3.6 million joules (3.6 x 10^6 J).
2. Step 2: To convert the energy usage from kWh to joules, multiply the given energy in kWh by the conversion factor (3.6 x 10^6 J/kWh).
3. Step 3: Calculate the energy in joules using the formula: Energy (J) = Energy (kWh) x 3.6 x 10^6 J/kWh.
4. Step 4: To convert joules to kilojoules (kJ), use the conversion factor where 1 kJ = 1000 J.
5. Step 5: Calculate the energy in kilojoules by dividing the energy in joules by 1000.

Key Concepts

Energy Units

Energy can be measured in various units, with the most common being joules (J) and kilowatt-hours (kWh). One kilowatt-hour is defined as the energy consumed by a power of one kilowatt running for one hour, which is equivalent to 3.6 million joules (3.6 x 10^6 J). Understanding these units is essential for converting energy values.

Conversion Factors

To convert between different units of energy, specific conversion factors are used. For instance, to convert kWh to joules, you multiply the number of kWh by 3.6 x 10^6. Similarly, to convert joules to kilojoules (kJ), you divide the number of joules by 1,000, since 1 kJ equals 1,000 J. Mastery of these conversion factors is crucial for accurate calculations.

Practical Applications of Energy Measurement

Understanding energy consumption in practical terms, such as in household appliances, helps in evaluating efficiency and cost. For example, knowing how much energy a refrigerator uses in kWh allows consumers to estimate their electricity bills and make informed decisions about energy-efficient appliances. This concept ties together the theoretical understanding of energy with real-world implications.