How to measure the calories of a candy with physics!

This Halloween when You pick up a candy, notice the wrapper. In the United States, a “Nutrition Facts” label has been required on all packaged foods since 1994, showing the serving size and amount of sugar, protein, fat, and sodium in the food. But the most interesting thing is the measurement of energy, which is listed as “calorie”. What does energy really mean when it comes to candy?

Flavors of energy

In physics, the concept of energy helps us to keep track of different types of interactions. We say that energy is conserved for all interactions, which means that if you calculate the total energy before and after something happens, that value will be constant.

During these interactions, energy can change from one form to another. I like to think of these as energy flavorings. There is the energy of a moving object, the flavor we call kinetic energy. Energy is stored in the gravitational field, a flavor we call gravitational potential energy. There is stored energy in the interaction between two charged particles or electric potential energy. And of course, when things get hot, thermal energy increases.

All types of energy are replaceable. How do you change energy from one flavor to another? I mean, we do that every day when we brew a pot of coffee. When electric current passes through a wire, the wire becomes hot. You can use this heat to increase the water temperature. (This is thermal energy.) We can calculate electrical energy by measuring the electrical current and voltage across the wire. This will be equal to the change in thermal energy of the water.

There is also a relationship between mechanical energy and thermal energy. Imagine you have a tank of water and you want to use rotating paddles to stir it. Your rowing system has three parts: the oars at the bottom, a length of rope in the middle, and a heavy weight that slides down the length of the rope. As gravity pulls the weight down along the rope, the paddles turn and push the water. This makes the water move, but the frictional interaction also heats the water. The change in the gravitational potential energy of the weight as it moves down the rope is equal to the change in the thermal energy of the water. The energy from the movement has been converted into heat energy.

joule, calorie, and calorie (other).

In physics, our preferred unit for energy is the joule. Historically, the amount of 1 joule can be defined as the energy that produces a force of 1 newton with a movement of 1 meter. A joule is also equal to the electrical energy resulting from a current of 1 ampere and a voltage of 1 volt for one second.

This unit can be difficult to understand, so try this simple experiment: Take a textbook and place it on the floor. Now take it and put it on the table. Since the book moved up, it gained more gravitational potential energy. The energy gain is approximately 10 joules. (The actual value depends on the height of the table and the mass of the book.)

Calorie is another unit of energy. It comes from the thermodynamic side of energy, so it is related to temperature changes. The value of one calorie is equal to the energy required to raise 1 gram of water by 1 degree Celsius.