When looking around supermarkets, we can see a variety of foods and drinks. We need to take in food and drink to ensure we have enough energy to carry out our daily activities. For example:
Energy can be transferred to different stores, but it is never used up. Food and drink store energy in the form of chemical energy. The amount of energy is often shown as a calorie (kcal), but the more scientific unit is joules (J) or kilojoules (kJ).
The food that we eat provides us with energy, which enables our body to perform all functions. The amount of energy in different foods can be found on their outer packaging, specifically on food labels. These food labels provide us with information about the food’s nutrients, which include fat, carbohydrates and salt.
Below is an example of this:
The energy section is shown on the label of the food item above. Each 150g serving of this food contains 1046 kJ of energy, which is the same as 250 kcal.
One calorie is the energy needed to raise the temperature of 1 g of water by 1 °C
Keep in mind that the energy listed might not be for the entire quantity of the food. As you can see in the food label above, the energy listed is for each 150 g serving.
Different amounts of energy are needed for different activities. For example:
Running could use up 3500 kJ per hour.
Resting could use up 350 kJ per hour.
Sleeping could use up 300 kJ per hour.
Fuels, such as oil, gas, coal and wood are all stores of energy. The energy stored in food and fuels is chemical energy.