The Joule (J) is the SI unit of energy. 1 calorie (cal) = 4.184 J; 1 Calorie (Cal) = 1000 cal = 1 kcal kJ=? J=?
The correct answer and explanation is:
Correct Answer:
1 kilojoule (kJ) = 1000 joules (J)
Explanation:
In the International System of Units (SI), the joule (J) is the standard unit for measuring energy. Energy can also be measured in other units like calories, kilocalories, and kilojoules depending on the context. Understanding the relationship between these units helps in scientific, nutritional, and engineering calculations.
A calorie (cal) is defined as the amount of energy required to raise the temperature of 1 gram of water by 1 degree Celsius. One calorie is equal to 4.184 joules (J). This conversion is used commonly in physics and chemistry.
A Calorie (Cal) with a capital “C,” also known as a kilocalorie (kcal), is often used in nutrition. It represents the energy required to raise the temperature of 1 kilogram of water by 1 degree Celsius. One Calorie equals 1000 calories, or:
1 Calorie (Cal) = 1000 cal = 4184 J
In energy calculations, kilojoules (kJ) are another commonly used unit. The prefix “kilo” in the metric system means 1000. Therefore, 1 kilojoule equals 1000 joules. This conversion is straightforward:
1 kJ = 1000 J
To summarize the relationships:
- 1 cal = 4.184 J
- 1 Cal = 1000 cal = 4184 J
- 1 kJ = 1000 J
These conversions are critical when analyzing energy in food, heat transfer in thermodynamics, or performing scientific experiments. Knowing how to switch between these units ensures accurate communication and computation in both academic and practical fields. For example, a nutrition label might show energy in kilojoules, but someone might want to convert it to Calories for easier understanding.