A fixed mass of gas in a thermally insulated container is compressed. After compression, the temperature of the gas will have:
Correct answer: D. Risen, since doing work on the gas increases the kinetic energy of the molecules
- A. Fallen, since more molecules bombarded the container and so they must be moving slower
- B. Fallen, since more molecules collide more frequently with one another and so their average speed is lower
- C. Remains constant if the compression is very slow
- D. Risen, since doing work on the gas increases the kinetic energy of the molecules
- E. Risen, since there are more intermolecular collisions and so more heat is produced by them
Explanation
If an ideal gas is compressed adiabatically, its temperature rises because the heat produced cannot be lost to the surroundings. Each molecule has more KE than before because of collisions of molecules with moving parts of the wall (i.e., piston compressing the gas).
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? [email protected]
About First Law of Thermodynamics
The first law relates heat supplied, work done and the change in internal energy through energy conservation. Problems use sign conventions and apply the law to isothermal, adiabatic, isobaric and isochoric processes. Internal energy is a state function, while heat and work depend on the path followed.
Practise Thermodynamics
714 free Thermodynamics MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Physics questions like this
Physics is on 16 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More First Law of Thermodynamics questions
A gas is enclosed in a container fitted with a piston of cross-sectional area of 0.10 m2. The pressure of the gas is maintained at 8000 N/m2. When heat is slowly transferred, the piston is pushed up through a distance of 4.0 cm. If 42 J heat is transferred to the system during the expansion, what is the change in the internal energy of the system?
The amount of heat at constant volume is called as:
The equation ΔU = ΔQ refers to:
With the usual notation, the first law of thermodynamics applied to one mole of an ideal gas can be written in the following form:CVΔT=ΔQ - PΔVIn a change for which Boyle's law is obeyed, which of the following would necessarily be zero?
The rapid escape of air from a burst tire is an example of:
A frictionless heat engine can be 100% efficient if: