Concept explainers
Whether the gain in organized kinetic energy, as a car burns more gasoline, contradicts second law of
Answer to Problem 1RQ
Solution:
No.
Explanation of Solution
Introduction:
Energy of an isolated system, such as the universe always remains constant, as stated by the law of conservation of energy. Energy is transformed into various forms such as disordered form of energy (thermal energy) or ordered form of energy (kinetic and potential energy).
Energy available in the universe is in ordered and disordered form. Although the energy is conserved at all times, only the energy thatcan be used to provide a useful work is of factual importance.
Second law of thermodynamics states that a system's ability to perform work depends upon the amount of organized form of energy present. Also, it is impossible to develop an engine thatcan convert all the disorganized form of energy (thermal energy) to useful work.
Explanation:
Gasoline is used to run the engine of the car. The engine of the car uses the chemical energy of the fuel and converts it into useful work to power the car. At first, this might seem to contradict the second law of thermodynamics, but it actually does not. This is because along with the useful work, a large amount of thermal energy is exhausted and energy in the form of sound is also lost (both being less organized form of energy), when gasoline is burnt.
So, as the car moves faster and faster, it does gain organized energy but for that more and more amount of fuel is burnt, which in turn increases the energy thatis lost to the environment. Hence, the organized form of energy (kinetic energy) gained by the car will never be more than that present in the gasoline (chemical energy).
The second law states that the ability to perform work depends upon the amount of organized form of energy present, so more the speed, more will be the amount of fuel burnt and more amount of energy will be lost.
Conclusion:
Therefore, burning of gasoline to gain organized kinetic energy does not contradict second law of thermodynamics.
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Chapter 16 Solutions
College Physics
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