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In our days, automobile has become a symbol of freedom and personal independance. With car keys in your hands you can go almost anywhere at a moment's notice.
What makes this instant transportation possible is the . It's basic design has changed little since it was invented more than a century ago. It uses thermal energy released by burning fuel to do the work needed to propel the car forward.
That thermal energy can do mechanical work in certain situations is one of the marvels of the thermal physics and the primary focus of this section.

Questions to think about:

  • Why are two objects, one hot and one cold, required in order to convert some thermal energy into useful work?
  • What hot and cold objects does a car have?
  • Why does a car have a cooling system to get rid of waste heat, rather than converting it into useful work?
  • Why does a car have different gears?

Experiments to do:

Take a moment to look under the of your car or that of a friend.
You should be able to identify the engine and it's electric support system. You should be able to count four or more spark plug wires this is a spark plug heading toward the engine's cylinders. These cylinders convert thermal energy from burning fuel into work to propel the car. Why does the engine need many cylinders instead of a big one?
At the front of the engine compartment, you'll find the How does this device extracts waste heat from the engine? Does heat flow naturally into the radiator and then into the outside air, or is there a heat pump involved?

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