3kg of water at 30°C is mixed with 0.5 kg of ice at -7°c. The specific heat for water is 4.187 kJ/kg°C, for ice 2.108 kJ/kgC. Calculate the amount of heat it would take to bring the ice from -7°C to 0°C. use
Question 9
9.
The heat it takes to warm the ice to 0°C cools the 30° water. What is the new temperature of the water?
Question 10
10.
How much heat does it take to melt 0.5kg of ice using the latent heat of fusion for water 336 kJ/kg
Question 11
11.
Using the heat you just calculated from the melting ice, what is the temperature of the water now?
Question 12
12.
Now we are mixing two different masses of water at two different temperatures to find the thermal equilibrium. You can set this up as
where x is the final temperature. solve for x.
Question 13
13.
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Question 14
14.
Read book pages 304-319 do you have any questions?
Question 15
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Question 16
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Question 17
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Question 18
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Question 19
19.
What does it mean that when energy is transformed it becomes less useful?
Question 20
20.
What is the relationship between the second law of thermodynamics and entropy
Question 21
21.
When air is quickly compressed, why does its temperature increase?
Question 22
22.
you cannot cool a kitchen by closing doors and windows but leaving the refrigerator open, but you can heat a kitchen by closing doors and windows and leaving an oven open. What is the difference?
Question 23
23.
Water evaporates from a salt solution and leaves behind salt crystals that have a higher degree of molecular order than the more randomly moving molecules in the saltwater. Has the entropy principle been violated? why or why not?
Question 24
24.
Why is it that 7 is the most common number to come up when someone is rolling two dice? And what does that have to do with thermodynamics?
Question 25
25.
Question 26
26.
A modern internal combustion engine has a theoretical efficiency of about 50%, but their actual efficiency is closer to 20-30%. What does that mean?
Question 27
27.
A carnot cycle operates between a heat reservoir of 300.0°C and ( -100.0°C). Calculate the ideal efficiency of the engine. give your answer in the form of a percentage with four significant digits.
Question 28
28.
Calculate the Carnot efficiency of an OTEC power plant that operates on the temperature difference between deep 4℃ and 25℃ surface water?
Review: Heat is best understood as
the movement of subatomic particles
the average kinetic energy of an object
How much energy it takes to increase a material by 1°C/kg
energy needed to vapoize or melt a material
Question 5
5.
Question 6
6.
Question 7
7.
We have talked about the three laws of thermodynamics before, see if you can match them to their more thermodynamic-y wording.
law 3 - you can't get out of the game
heat added to the system = increase of internal energy +external work done by the system
law 1 - you can't win
Heat will never flow from cold to hot by itself
Law 2 - you can't break even
The entropy of a system at absolute zero is a well defined constant
Vocab question 1 - Aidabatic process is one
Where upward convection of air is stopped
where no heat enters of leaves a system
heat is used as an input and supplies mechanical work as output
the temperature is reduced to the lowest possible temperature a substance can have
vocab question 2 - a heat engine
restates the law of conservation of energy
a meteorological event where the upper region of atmosphere is warmer than the region below it
takes heat and transforms it to mechanical enery
moves heat from a cool place to a relatively warmer place
Which type of system transfers heat from a colder reservoir to a hotter reservoir?
Internal Combustion Engine
Air Conditioner
Steam Turbine
Refrigerator
Heat Engine
Heat Pump
If work is done on a system, does the internal energy of that system increase or decrease?
increase
decrease
an engine's efficiency can be, at most, 100% and then only really in ideal physics land