EATING ENERGY (Grade 9-12)

About 1550 calories are needed to make the aluminum can that holds diet soda. Zero calories are in the soda, so...if you wanted to get maximum energy, you would eat the can!

The unit of heat used in science is the calorie (cal.), also called gram-calorie or small calorie. It is defined as the amount of heat energy needed to raise one gram of water 1 degree centigrade.

In nutrition, the unit of food energy is the Calorie (Cal.), also called kilogram-calorie, or great calorie. It is defined as the amount of heat needed to raise one Kilogram of water 1 degree centigrade. It is equal to 1000 calories.

The small c, capital C difference is important. Only the nutritional calorie uses capital C.

Engineers use a different heat energy standard called the British Thermal Unit (BTU). It is defined as the amount of energy required to raise one pound of water 1 degree fahrenheit. One BTU = 252 calories.

Conversions
1 pound = 454 grams
degree C = 5/9 (degree F - 32)
1 kilogram = 2.2 pounds

PROCEDURE: For each food item listed in TABLE 2:

  1. In the first (leftmost) entry column, enter the weight of the dry, empty packaging used for the food.

  2. Record the unit price of the packaging in the second entry column. The unit prices are listed in Table 1.

  3. Determine the amount of energy required to rpoduce the packaging for the food by multiplying the actual container weight by the energy per unit weight of container.

  4. In the far right column, enter the price (current value) of the food listed

  5. Compare the costs of similar amounts of a specific food item based on how it was packaged. Compare the amount of energy needed to package the same amount of a product in different ways.

TABLE 1. Energy used to produce packaging materials
MaterialKCAL/LBKCAL/OZKCAL/GM BTUS/LBTUS/GM
Paper5,13432111.4 20,37344.9
Glass1,9181204.27,611 16.8
Steel3,7242338.314,778 32.6
Aluminum24,8371,55254.7 98,560217.1
Plastic4,67029210.318,532 40.8

TABLE 2: Comparison of packaging types
Food Item Package
Weight
Energy Cost /
unit weight
of container
Energy for
Container
(KCAL)
Price of
Food Item
($)
Fresh green beans (1 lb)
Canned green beans (1 lb)
Frozen green beans (1 lb)
Frozen concentrated apple juice
Bottled Apple juice (1-2 quarts)
Canned Apple juice (1-2 quarts)
6-pack of Apple Juice in aluminum cans


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