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Energy is often converted or transformed from one kind to another, but the total energy is always conserved. The principle that energy cannot be created or destroyed but is always conserved is known as the first law of thermodynamics. Thermodynamics is the science that keeps track of energy as it undergoes various transformations from one type to another.

 

We use the first law to keep track of the quantity of energy. In pushing your stalled car, you have moved it against gravity and caused some of its parts brakes, tires, bearings to be heated. These effects have something in common: They are forms of energy. You have converted chemical energy in your body to the energy of motion of the car kinetic energy.

 

When the car is higher on the hill, the potential energy of the car has been increased, and friction produces heat energy. They argue that the way to solve these environmental problems is to provide cheap, high-quality energy, such as fossil fuels or nuclear energy. In countries like the United States, with sizable resources of coal and natural gas, people supporting the business-as-usual path argue that we should exploit those resources while finding ways to reduce their environmental impact.