Hello could someone please help me with the following problem, its about thermodynamics. its urgent, thanks!!!?

Question by : Hello could someone please help me with the following problem, its about thermodynamics. its urgent, thanks!!!?
An electric pressure cooker is fitted with a 10.75 ohms resistance, and connected to a 127-V outlet. The cooker is originally filled with 2.5 kg of ice at -15º C. At t = 0, the device is turned on. The safety valve is set up so a constant pressure of 1 atm. will exist within the cooker at all times, and it may be assumed that all the energy produced by the resistance is transmitted to the ice and/or water in the cooker, and that there is no energy exchange with the environment. You are asked to do the following:
Calculate the time at which all the ice will be melted, and the time at which all the water inside the cooker will be evaporated.


Best answer:

Answer by Felicia
law of energy conservation

Qin = Qout
Q input is the electric pressure cooker. it has power P=V.I= V. (V/R) = V^2.R. power is energy flow per time unit, so input energy Qin = P.t = V^2.R . t
Q output is the energy, in the form of heat, transferred to the ice. we need to know how much energy in heat form is needed to melt m= 2.5kg of T1= -15 C ice
ice melting at 0 C...there is dualism at 0 degree celcius; water can either be in solid form, or liquid/melted form.
first we need to calculate the energy needed to increase the temperature of ice from T1= -15 to T2= 0 C.
the formula is Q ice = m.c. (T2 - T1) where c is heat capacity of ice. you can google it.
now we have 2.5kg of 0 degree C ice. now we need to melt it. in state transforming process, there is no change of temperature, since the energy is used for transforming, in this case, ice to water
the amount of energy needed for this transformation is:
Q melt = m.L where L is the amount of energy in KJ or J needed in order to transform one kilogram of ice to water. google it too.
so the total energy needed to melt the ice is
Qout = Q ice + Q melt = m.c.(T2 - T1) + m.L

Qin = Q out
V^2.R. t = m.c.(T2 - T1) + m.L

there it is, you get t. t is the amount of time you need to melt the ice using your pressure cooker.

to find the time at which all water will be evaporated, the same thing goes for second process. but note these: now the initial temperature of the water is T1= 0 C we want to have this water transformed to steam, that is T2= 100 C,
and now L is the amount of energy in KJ or J needed in order to transform one kilogram of water to vapour.


sorry no calculation, i don't have my calculator at hand. hope this clear enough

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Moms, save my rump roast please?

Question by Leah's Mommy: Moms, save my rump roast please?
Ok. I have a 3 pound rump roast. Should I throw it in the crock pot? I don't have any beef broth or cream of mushroom soup. I do have some carrots but thats it. Should I pressure cook it after I season it? Help!

PS - FWIW, I have an electric pressure cooker.


Best answer:

Answer by Flo
I wish I could help. But I have yet to cook a roast that isn't closer to jerky than real food. :)

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help recipe for making bulgarian rakia please?

Question by bronco: help recipe for making bulgarian rakia please?



Best answer:

Answer by Chloe
The traditional Rakia is acquired by the distillation of fruits or wines in a special metal pot. It is heated by setting up a small fire underneath the pot. The first thing that will come out of the pot is a substance rich with methyl achohol, you should throw it away as it’s poisonous. You should get 1/2 litre of this substance when boiling 100 litres of fruits or wines.

The main ingriedients for the Rakia should have a fine taste, not too sweet, sour or bitter. The bitter taste means that it more than 5 months old. The fire underneath the bot shouldn’t be very big, otherwise you’ll burn the whole mixture.

Rakia ( cyr. Ракия ) is considered to be the national drink in Bulgaria and all the other Slavic Balkan nations. It has a very high alchohol content and is made by distillation of fermented fruits like plums, grapes, apples, quinces and other. Most people in rural areas make Rakia at home, therefore it’s alchohol content can reach 60% or more. It’s usually consumed with shopska salada, pickles, turshia. The Rakia is often compared to brandy and vodka.
To make rakia you will need a still. Obviously the ideal would be a copper pot still, but if you want to go cheap, get an electric pressure cooker (do not use a stove top model, as there is a significant fire/explosion risk). Where the valve is, you will need to hook up some surgical tubing. The tubing then connects to a coiled copper tube in a bucket filled with ice water. The copper coil pokes through a hole in the side, where a glass catches the distilate.

Generally you will want to throw out the heads, the first part of the output (first quarter inch or so), because if the wine you used wasn't fermented properly (rare, but can happen), you can get toxic methanol in your brew. The tails (when too much water gets in, also gets thrown out, as it tastes less than ideal). Many distillers put the heads and tails into the next batch.

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How to self tattoo? PLEASE ANSWERR?

Question by anniee_x: How to self tattoo? PLEASE ANSWERR?
I'm 14 in June and want a little tattoo in a secret type place, both of my parents have done tattoos themselves with indian ink, i was thinking of doing the same.. Where could i get indian ink from?
And please don't give me all the ''Don't do it it'll kill you s***''

And how could i self tattoo myself perhaps?
I only want a little one in a place not many people will see, like my wrist or hip.


Best answer:

Answer by Kyle B
You can use a needle, which will take forever, or buy a gun which will make it much faster. You must be careful for infection if you do it yourself.

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Can someone give me the Recipe to make a cake from scratch please!!!!?

Question by Gina Serrato: Can someone give me the Recipe to make a cake from scratch please!!!!?



Best answer:

Answer by Cassie Cates
Ingredients:

3 cups sifted cake flour
2 1/2 teaspoons baking powder
1/2 teaspoons salt
1 3/4 cups sugar
2/3 cup butter or margarine
2 eggs
1 1/2 teaspoons vanilla
1 1/4 cups milk

Makes:

Cake serves 12.
Instructions:
Step 1

Preheat oven to 350°F. Grease bottom of two 8-inch round cake pans and line with waxed paper or parchment paper. Sift together flour, baking powder and salt; set aside. Cream sugar and butter together until light. Add eggs and vanilla to creamed mixture and beat until thoroughly mixed. Add flour mixture to creamed mixture alternately with milk, beating well after each addition. Continue beating one minute. Spread batter evenly in prepared pans. Bake 30 to 35 minutes or until wooden pick inserted in center comes out clean. Cool layers in pans on wire racks 10 minutes. Remove from pans; cool completely. Fill and frost as desired.

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Save my rump roast please!?

Question by Leah's Mommy: Save my rump roast please!?
Ok. I have a 3 pound rump roast. Should I throw it in the crock pot? I don't have any beef broth or cream of mushroom soup. I do have some carrots but thats it. Should I pressure cook it after I season it? Help!

PS - FWIW, I have an electric pressure cooker.


Best answer:

Answer by Biff Beltsander
My wife LOVES cooking rosts in the electric cock pot. Put some seasonings on it and your carrots and you may have a very nice meal.

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