Physics HELP!

[Vulture]

I need help with Physics. This is do tomorrow! Anyone up for the challenge?


1. Would opening a refrigerator door on a warm day help to cool the kitchen? Explain.

2. In each of the following examples, determine if there is an increase, decrease or no change in the system's entropy

a. A hot fudge sundae is left uneaten too long, so that hte ice cream melts and the fudge solidifies.

b. A green plant combines water and carbon dioxide molecules in photosynthesis to make a larger, more complex molecule of sugar.

c. You drop your research paper on the way up the stairs and find that, when you have gathered all the pages, they are no longer in sequence.

d. All the perfume in an opened bottle evaporates and fills the room with scent.

e. A shortage of library personnel makes it increasingly difficult to find the books you want in their proper locations on the shelves.


3. A container of steam containing 0.65 kg at 185.0 degrees Celsius expands, doing work by moving a piston which exerts a force of 450 N over a distance of 2.11 m. What is the final temperature of the steam?





This has to do with Thermal Energy and Entropy Will someone please explain these answer to me?

 

[brucevangeorge]

I WOULD. But you would have to know what entropy is. Now, I'm not going to do your work for you but I will explain entropy to you.

Entropy is a measurte of disorder in a system. Eg. The human body. It is made up of THOUSANDS of different chemicals, this is a disorder. Whereas a piece of metal is very orderly. It is made of one element. NOW. It takes energy in order to increase entropy and energy to keep entropy high. Without energy something like the human body would decrease in entropy. This means that if you dont eat (energy in the system) you will degrade into the basic and simplest elements C, N, O, H, and traces of others.

This is all the info I'm giving you. Don't bother asking for more. Look up the laws of thermodynamics if you want it to be clearer. Its called a textbook. Use it.

 

[Vulture]

^ Thanks for the help

I know what entropy is. But thanks for giving me a review it up for me.


Could you tell me if I am right about these answers:


1. Heat travels from hot to cold. Refrigerator is cold. Warm kitchen is hot. The heat from the kitchen travels into the refrigerator. Thus, kitchen looses it's warm heat.

2.
a. increase
b. decrease
c. increase
d. increase
e. increase


3. (I'm still trying to figure this one out.)

 

[Le Parisien]

Ok let me try...


1) NO. Otherwise everybody would be doing it.
In more familiar terms, the electricicty that is consumed creates more heat than "the cold" that is created, the temperature of the room will rise.
In more scientific terms. The refrigerating process transfers some of the enthalpy (energy, heat, whatever...) from the inside to the outside of the fridge. So far it's balanced, no loss no gain. But at the same time the process creates entropy, so overall you will gain energy in the room.
If you don't need an explanation but just a proof: electricty (energy) comes into the system, nothing goes out, so energy will increase, temperature goes up.

2)
First of all, one of the rules of thermodynamics says entropy can only increase. Bascially to see if the entropy stays the same or if the entropy goes up, you need to determine if the transformation is reversible. If it is, entropy is constant, otherwise it increases.
a) It increases
b) I'd say Constant, but I'm NOT a specialist in Biology
c) Constant
d) It increases
e) Constant

3)
Ok this is the equation you need to use "VAN DER WAALS equation", make your own calculations.
"P*V = n*R*T"
P pressure
V volume
T temperature
R a constant
n molar number


Hope this helps...

And God bless the Excellent French Education System !!!

7 years later, I still remember. Because I never learned anything by heart, everything was UNDERSTOOD...

Ha I'm so proud of myself...

 

[Create Reality]

Originally posted by Vulture
I need help with Physics. This is do tomorrow!

Originally posted by Vulture
... is do tomorrow!

Originally posted by Vulture
... do ....

:cheer: GO TEAM! :cheer:

 

[Vulture]

Re: Re: Physics HELP!

Originally posted by Create Reality
:cheer: GO TEAM! :cheer:

:crackup:

I didn't realize my mistake!

:crackup:

 

[Vulture]

Originally posted by Vulture


3. A container of steam containing 0.65 kg at 185.0 degrees Celsius expands, doing work by moving a piston which exerts a force of 450 N over a distance of 2.11 m. What is the final temperature of the steam?

Please will someone explain this to me?

 

[Le Parisien]

I edited my reply, so now you have evrything.
To your calculator boy !!!

 

[aBAzLLnA]

Well look at the different equations you have. What comes to mind right now is conservation of energy. Try that out.

I really hate physics lol. Used to be my major, now i'm a psych major.

 

[B-Lemond]

Originally posted by Le Parisien
I edited my reply, so now you have evrything.
To your calculator boy !!!

HAHA :crackup: :crackup:

 

[Centaurion]

I should know this since I had Thermodynamics and Fluids as one of my engineering classes last semester.

But I'm too lazy to type everything up.

 

[diablo]

Sorry, but as said several times before, this forum is not for help with people's homework.