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wec01 wrote:

mjcox2000 wrote:

UTF-8 U+6211 U+662F wrote: I'm confused how the reservoirs could reach equilibrium? The Carnot cycle assumes that the reservoirs will never change temperature.

The Carnot cycle doesn’t require constant-temperature reservoirs.

Hint (Click to Show Hidden Text)

The Carnot efficiency equation predicts the instantaneous efficiency. Try integrating.

Answers (assuming I used that hint right): (Click to Show Hidden Text)

1. 252 K
2. 5920 J
3. 2880 J
4. 48.6 %

It should be 51.4% — I assume you found the percentage of wasted energy, not usable energy.

wec01 wrote:Suppose you had a cylinder with a piston in it. Describe how you would cause the system to undergo:
1. adiabatic expansion
2. isothermal expansion
3. isobaric expansion

1. Quickly pull on the piston
2. Submerge the cylinder in a constant-temperature water bath and slowly pull on the piston
3. Heat the cylinder and don’t touch the piston

mjcox2000 wrote:

wec01 wrote:Suppose you had a cylinder with a piston in it. Describe how you would cause the system to undergo:
1. adiabatic expansion
2. isothermal expansion
3. isobaric expansion

Answer (Click to Show Hidden Text)

1. Quickly pull on the piston
2. Submerge the cylinder in a constant-temperature water bath and slowly pull on the piston
3. Heat the cylinder and don’t touch the piston

mjcox2000 wrote:A sample of air starts at STP. Then, a sound source emitting a 10kHz sine wave is placed in the sample of air. At a certain point P at a given distance from the sound source, the RMS sound pressure level is 100 dB. Assuming air behaves adiabatically when sound travels through it and there are no frictional losses, what is the minimum and maximum temperature at point P?

[math]\pm 9.2 * 10^{-3} ^{\circ} C[/math]

wec01 wrote:

mjcox2000 wrote:A sample of air starts at STP. Then, a sound source emitting a 10kHz sine wave is placed in the sample of air. At a certain point P at a given distance from the sound source, the RMS sound pressure level is 100 dB. Assuming air behaves adiabatically when sound travels through it and there are no frictional losses, what is the minimum and maximum temperature at point P?

Not sure if I approached this right, but I got (Click to Show Hidden Text)

[math]\pm 9.2 * 10^{-3} ^{\circ} C[/math]

wec01 wrote:

wec01 wrote:

mjcox2000 wrote:A sample of air starts at STP. Then, a sound source emitting a 10kHz sine wave is placed in the sample of air. At a certain point P at a given distance from the sound source, the RMS sound pressure level is 100 dB. Assuming air behaves adiabatically when sound travels through it and there are no frictional losses, what is the minimum and maximum temperature at point P?

Not sure if I approached this right, but I got (Click to Show Hidden Text)

[math]\pm 9.2 * 10^{-3} ^{\circ} C[/math]

Oops, I see an error in my work; working on fixing it

[math]\pm 7.6 * 10^{-3} ^{\circ} C[/math]