A gas in a cylinder is compressed by a movable piston to half its initial volume, rejecting 300 kJ of heat while internal energy remains constant. What is the work done on the gas in N·m___________________?
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Answer: B. 300,000 Nm
Explanation
For an isothermal process with constant internal energy, work done equals the heat rejected. Heat rejected of 300 kJ converts directly to 300,000 Joules or N·m of work. Mathematical conversion from kilojoules to newton-meters yields the correct numerical value. The first law of thermodynamics states that net heat transfer equals net work done in a constant energy cycle. One kilojoule is equal to one thousand joules, which correspond directly to newton-meters. Isothermal compression processes maintain constant temperature while pressure and volume change inversely.
Compressor thermodynamic analysis requires accurate calculation of work input during gas compression. Understanding energy balances helps engineers design efficient pneumatic systems and refrigeration units. Conversion between energy units is a fundamental skill in mechanical and thermal engineering practice. Option A forgets the scale factor of one thousand when converting kilojoules to joules. Option C uses an incorrect decimal placement during the energy unit conversion process. Option D and E miscalculate the magnitude by adding or removing extraneous decimal places.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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