Thermodynamics B/C

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Re: Thermodynamics B/C

Post by smayya337 » February 28th, 2019, 9:18 am

mjcox2000 wrote:What type of heat engine can a hurricane be likened to? What is its source of heat and where does it exhaust the heat to? Assuming typical temperatures, pressures, etc. for the source of heat and exhaust (you may want to look up these typical values), what is its theoretical maximum efficiency?
A hurricane is a Carnot engine, since there's no fuel, just heat. Its source of heat is the tropical water, and its exhaust is the atmosphere. The temperature at the water's surface is 20°C and the temperature at the top of the hurricane is -40°C, giving an efficiency of 79.53%. Then you came over and reminded me that you need to subtract the value from one, so the actual Carnot efficiency is 20.47%.
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Re: Thermodynamics B/C

Post by mjcox2000 » February 28th, 2019, 9:25 am

smayya337 wrote:
mjcox2000 wrote:What type of heat engine can a hurricane be likened to? What is its source of heat and where does it exhaust the heat to? Assuming typical temperatures, pressures, etc. for the source of heat and exhaust (you may want to look up these typical values), what is its theoretical maximum efficiency?
A hurricane is a Carnot engine, since there's no fuel, just heat. Its source of heat is the tropical water, and its exhaust is the atmosphere. The temperature at the water's surface is 20°C and the temperature at the top of the hurricane is -40°C, giving an efficiency of 79.53%. Then you came over and reminded me that you need to subtract the value from one, so the actual Carnot efficiency is 20.47%.
Than looks right and the values seem reasonable enough. Your turn!
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Re: Thermodynamics B/C

Post by wec01 » February 28th, 2019, 9:46 am

mjcox2000 wrote:
smayya337 wrote:
mjcox2000 wrote:What type of heat engine can a hurricane be likened to? What is its source of heat and where does it exhaust the heat to? Assuming typical temperatures, pressures, etc. for the source of heat and exhaust (you may want to look up these typical values), what is its theoretical maximum efficiency?
A hurricane is a Carnot engine, since there's no fuel, just heat. Its source of heat is the tropical water, and its exhaust is the atmosphere. The temperature at the water's surface is 20°C and the temperature at the top of the hurricane is -40°C, giving an efficiency of 79.53%. Then you came over and reminded me that you need to subtract the value from one, so the actual Carnot efficiency is 20.47%.
Than looks right and the values seem reasonable enough. Your turn!
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Re: Thermodynamics B/C

Post by smayya337 » February 28th, 2019, 2:02 pm

1) Find the spectral radiance of a black-body, provided that the frequency of radiation is 700Hz and the temperature is 14000K.
2) Find the radiant exitance of a black surface at 0°C.
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Re: Thermodynamics B/C

Post by wec01 » February 28th, 2019, 2:50 pm

smayya337 wrote:1) Find the spectral radiance of a black-body, provided that the frequency of radiation is 700Hz and the temperature is 14000K.
2) Find the radiant exitance of a black surface at 0°C.
1) 2 x 10^-30 (1 sig fig)
2) 315 W/m^2 (3 sig figs)
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Re: Thermodynamics B/C

Post by smayya337 » February 28th, 2019, 3:03 pm

wec01 wrote:
smayya337 wrote:1) Find the spectral radiance of a black-body, provided that the frequency of radiation is 700Hz and the temperature is 14000K.
2) Find the radiant exitance of a black surface at 0°C.
1) 2 x 10^-30 (1 sig fig)
2) 315 W/m^2 (3 sig figs)
You're correct!
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Re: Thermodynamics B/C

Post by wec01 » March 1st, 2019, 2:05 pm

Here is a relatively straightforward question:

A 100g ice cube at -10 degrees Celsius is added to 100g of water at 10 degrees Celsius.
1) What is the final state of the solution (phase of matter and temperature)?
2) Why doesn't the solution simply become a mixture of ice and water at 0 degrees Celsius?
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Re: Thermodynamics B/C

Post by Crimesolver » March 1st, 2019, 5:03 pm

wec01 wrote:Here is a relatively straightforward question:

A 100g ice cube at -10 degrees Celsius is added to 100g of water at 10 degrees Celsius.
1) What is the final state of the solution (phase of matter and temperature)?
2) Why doesn't the solution simply become a mixture of ice and water at 0 degrees Celsius?
1) It is a liquid at 3.3 Celsius
2)This is because ice has a lower specific heat, which means it melts and heats up more easily.
Last edited by Crimesolver on March 1st, 2019, 5:38 pm, edited 1 time in total.
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circuits: 12/2/9/12/6/10/
Keep on going :)

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Re: Thermodynamics B/C

Post by UTF-8 U+6211 U+662F » March 1st, 2019, 5:34 pm

Crimesolver wrote:
wec01 wrote:Here is a relatively straightforward question:

A 100g ice cube at -10 degrees Celsius is added to 100g of water at 10 degrees Celsius.
1) What is the final state of the solution (phase of matter and temperature)?
2) Why doesn't the solution simply become a mixture of ice and water at 0 degrees Celsius?
1) It is a liquid at 3.3 Celsius 
2)This is because ice has a lower specific heat, which means it melts and heats up more easily.
Reminder to use the
 or [hide] tags for answers in case anyone wants to follow along

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Re: Thermodynamics B/C

Post by Crimesolver » March 1st, 2019, 5:37 pm

UTF-8 U+6211 U+662F wrote:
Crimesolver wrote:
wec01 wrote:Here is a relatively straightforward question:

A 100g ice cube at -10 degrees Celsius is added to 100g of water at 10 degrees Celsius.
1) What is the final state of the solution (phase of matter and temperature)?
2) Why doesn't the solution simply become a mixture of ice and water at 0 degrees Celsius?
1) It is a liquid at 3.3 Celsius 
2)This is because ice has a lower specific heat, which means it melts and heats up more easily.
Reminder to use the
 or [hide] tags for answers in case anyone wants to follow along
Ooof totally forgot, was excited that I kinda knew the answer to this one
cerritos/great oak/SOLVI/poly/wilson/r/s(!) (well this sucks)
detector: 1/2/1/12/27/1/
machines: 13/10/9/10/3/10/
sounds: 26/15/13/12/3/7/
gravity: 11/8/3/6/9/8/
circuits: 12/2/9/12/6/10/
Keep on going :)

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