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nikklg [1K]
3 years ago
11

A thermoelectric refrigerator is powered by a 16-V power supply that draws 2.9 A of current. If the refrigerator cools down 3.1

kg of water from 25 °C to 11 °C in 12 hours, what is the average COP of the refrigerator? Take the specific heat of water as 4180 J/kg.K. (3 decimal digits)
Engineering
1 answer:
Viktor [21]3 years ago
8 0

Answer:

COP = 0.090

Explanation:

The general formula for COP is:

COP = Desired Output/Required Input

Here,

Desired Output = Heat removed from water while cooling

Desired Output = (Specific Heat of Water)(Mass of Water)(Change in Temperature)/Time

Desired Output = [(4180 J/kg.k)(3.1 kg)(25 - 11)k]/[(12 hr)(3600 sec/hr)]

Desired Output = 4.199 W

And the required input can be given as electrical power:

Required Input = Electrical Power = (Current)(Voltage)

Required Input = (2.9 A)(16 V) = 46.4 W

Therefore:

COP = 4.199 W/46.4 W

<u>COP = 0.090</u>

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Electric current originates from which part of an atom? *
yanalaym [24]

Answer: Electric current originates from positively charged protons negatively charged electrons of an atom.

Explanation:

The movement of ions (positive or negative) from one point to another is called electric current.

An atom has three sub-atomic particles. These are protons, neutrons and electrons.

Protons are positively charged, neutrons have no charge and electrons are negatively charged. Protons and neutrons reside inside the nucleus of an atom whereas electrons revolve around the nucleus.

So, protons and electrons are responsible for originating electric current form an atom as these are the charged particles.

Thus, we can conclude that electric current originates from positively charged protons negatively charged electrons of an atom.

3 0
3 years ago
The longest_word function is used to compare 3 words. It should return the word with the most number of characters (and the firs
NARA [144]

Answer:

len(word2) >= len(word1) and len(word2) >= len(word3):

Question with blank is below

def longest_word(word1,word2,word3):

   if len(word1) >= len(word2) and len(word1) >= len(word3):

       word = word1

   elif _________________________________________

       word = word2

   else:

       word = word3

   return word

print(longest_word("chair","couch","table"))

print(longest_word("bed","bath","beyond"))

print(longest_word("laptop","notebook","desktop"))

print(longest_word("hi","cat","Cow"))

Explanation

In line 1 of the code word1, word2, and word3 are the parameters used to for the defining the longest_word function. They will be replaced by 3 words to be compared. The code that is filled in the blank is len(word2) >= len(word1) and len(word2) >= len(word3): It is a conditional statement that is true only if the number of characters in the string of word2 is greater than or equal to word1 and word2 is greater than that of word3 .

4 0
3 years ago
Which of the following is NOT a risky food:
Lyrx [107]

i think it's c. bread.

3 0
3 years ago
Read 2 more answers
For some metal alloy it is known that the kinetics of recrystallization obey the Avrami equation, and that the value of k in the
JulsSmile [24]

Answer:

t = 1456.8 sec

Explanation:

given data:

contant k = 2.60*10^{-6}

rate of crystallization is 0.0013 s-1

rate of transformation is given by

r = \frac{1}{t_0.5}

use specifies value to solve t_0.5

it is ime required for 50% tranformation

r = \frac{1}{.0013}=769.2 sec

Avrami equation is given by

y = 1 - e^{-kt^n}

0.5 = 1 - e^{-kt_0.5^n}

1-0.5 = e^{-kt_0.5^n}

ln (1 - 0.5) = -kt_0.5^n

ln \frac{ln (1 - 0.5)}{-k} = nln t_0.5

n = \frac{ ln \frac{ln (1 - 0.5)}{-k}}{ln t_0.5}

n = \frac{ ln \frac{ln (1 - 0.5)}{-2.60*10^{-6}}}{ln 769.2}

n = 1.88

second degree of recrystalization may be determine by rearranging original avrami equation

t = [\frac{-ln(1-y)}{k}]^{1/n}

for 90%completion

t = [\frac{-ln(1-0.9)}{2.60*10^{-6}}]^{1/1.88}

t = 1456.8 sec

5 0
3 years ago
Fill in the correct answer.
mestny [16]

Answer:

Explanation:

A conservator with a(n) guardianship background and knowledge of foreign languages will have more job opportunities because they broaden the scope of work a conservator can undertake.

6 0
2 years ago
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