What is a calorie in terms of energy?

What is a calorie in terms of energy?

• A. A unit of energy equal to one joule.
• B. A unit of energy; specifically, a kilocalorie (kcal) is 1,000 scientific calories.
• C. A unit of mass.
• D. A unit of temperature.

Answer: (B)

Energy is the key idea here. A calorie is a unit of energy—the amount of energy required to heat something. In physics and chemistry, a small calorie is defined as the energy needed to raise the temperature of 1 gram of water by 1 degree Celsius, which is about 4.184 joules. In nutrition, what’s labeled as a “calorie” is actually a kilocalorie: 1 kilocalorie equals 1,000 of those small calories (1 kcal = 1000 cal = 4184 J). That’s why food labels show calories with a capital C, and a value like 200 Calories means 200 kilocalories, or 200,000 small calories. So the correct description is that a calorie is a unit of energy, and in nutrition, the term corresponds to a kilocalorie. It is not a unit of mass, not a unit of temperature, and not equal to one joule.

Energy is the key idea here. A calorie is a unit of energy—the amount of energy required to heat something. In physics and chemistry, a small calorie is defined as the energy needed to raise the temperature of 1 gram of water by 1 degree Celsius, which is about 4.184 joules.

In nutrition, what’s labeled as a “calorie” is actually a kilocalorie: 1 kilocalorie equals 1,000 of those small calories (1 kcal = 1000 cal = 4184 J). That’s why food labels show calories with a capital C, and a value like 200 Calories means 200 kilocalories, or 200,000 small calories.

So the correct description is that a calorie is a unit of energy, and in nutrition, the term corresponds to a kilocalorie. It is not a unit of mass, not a unit of temperature, and not equal to one joule.