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Making Heat
How do you make heat? You could burn things, there could be chemical reactions, or you could rub things together and create heat from friction. When you burn things, thermal energy is released. Thermal energy is measured in calories. For example, when you burn wood, you release 3000 calories for each gram of wood. When you burn an apple, it creates only 600 calories. The amount of energy released is directly related to the amount of energy stored up in the chemical bonds. If you use that idea, there is more energy stored in the bonds of a piece of wood than in the bonds of an apple.
Losing Energy
We just talked about friction. Heat is also created because of inefficiency. When a car engine runs, a lot of heat is given off. Much of that heat is the result of the friction and inefficiency in the running motor. When you lift something and your muscle contracts, you are only 25% efficient. Seventy-five percent of the energy is lost to heat.
More Transfer of Energy
Heat is the thermal energy transported from one system to another because of a temperature difference. The transfer of that energy stops when the temperature balances out in the entire environment. Scientists use the unit of a calorie to measure heat. You might be saying, "I've heard of calories. Are those like the ones in food?" The answer is "Yes." One calorie is measured as the amount of energy needed to raise the temperature of one gram of water, one degree Celsius. When you are burning calories you are actually using the energy stored in your food.
Specific Heat Capacity
There is also something totally important called specific heat capacity. Remember that we just talked about one calorie? Specific heat works the same way. It is the amount of energy required to raise the temperature of one gram of substance one degree Celsius. So the specific heat capacity for water is one. As we said, heat is a form of thermal energy. Because it's energy, scientists also use the units of Joules to measure the energy. One calorie equals 4.186 Joules which also equals 4.186 Watts seconds (Ws). Does that mean you can measure the amount of energy you make in you body in terms of an electric value (Watts)? Yes, your energy can be converted into electrical work.
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