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Genrish500 [490]
2 years ago
5

The temperature inside a Carnot refrigerator placed in a kitchen at 22 degree Celcius is 2 degree Celcius. The heat extracted fr

om the refrigerator is 89 MJ/h. What power is needed to operate this refrigerator?
Physics
1 answer:
Elanso [62]2 years ago
4 0

Answer: 1.79 kW

Explanation:

Given

The temperature of the refrigerator is T_L=2^{\circ}C\approx 275\ K

The temperature of the kitchen is T_H=22^{\circ}C

COP of the refrigerator is

COP=\dfrac{T_L}{T_H-T_L}=\dfrac{\text{Desired effect}}{\text{Power}}\\\\\Rightarrow COP=\dfrac{275}{22-2}=\dfrac{89}{P}\\\\\Rightarrow P=\dfrac{20}{275}\times 89=6.47\ MJ/h\ \text{or}\ 1.79\ kW

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sergejj [24]

Here mass of the iron pan is given as 1 kg

now let say its specific heat capacity is given as "s"

also its temperature rise is given from 20 degree C to 250 degree C

so heat required to change its temperature will be given as

Q = ms \Delta T

Q = 1*s*(250 - 20)

Q = 1*s*230

now if we give same amount of heat to another pan of greater specific heat

so let say the specific heat of another pan is s'

now the increase in temperature of another pan will be given as

Q = ms'\Delta T

1*s*230 = 1* s' * \Delta T

now we have

\Delta T = (\frac{s}{s'})*230

now as we know that s' is more than s so the ratio of s and s' will be less than 1

And hence here we can say that change in temperature of second pan will be less than 230 degree C which shows that final temperature of second pan will reach to lower temperature

So correct answer is

<u>A) The second pan would reach a lower temperature.</u>

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2 years ago
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Which statement describes something that should always be done at the end of a calculation?
Reika [66]

Answer:

C) Check that the numerical answer is reasonable and the units are what you expected.

Explanation:

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3 years ago
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A book that weighs 19 Newtons sits on a table. With what force
iVinArrow [24]

Answer:

We know there's two forces acting on a book while it sits on a table:the force of gravity pulling it down, and the normal force of the table acting upward on the book. The book isn't accelerating while it sits there. That's because the weight of the book is being counteracted by the normal force of the table.

Explanation:

There are two forces acting upon the book. One force - the Earth's gravitational pull - exerts a downward force. The other force - the push of the table on the book (sometimes referred to as a normal force) - pushes upward on the book.

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To solve this problem we will apply the concepts related to the balance of Forces, the centripetal Force and Newton's second law.

I will also attach a free body diagram that allows a better understanding of the problem.

For there to be a balance between weight and normal strength, these two must be equivalent to the centripetal Force, therefore

F_c = W-N

m\omega^2r = W-N

Here,

m = Net mass

\omega= Angular velocity

r = Radius

W = Weight

N = Normal Force

m\omega^2r = 174-146

The net mass is equivalent to

F = mg \rightarrow m = \frac{F}{g}

Then,

m = \frac{174lb}{32.17ft/s^2}

Replacing we have then,

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What is the speed of the object at the end of 10 s?
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-100m/s not shure tho thx tho

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