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Xelga [282]
3 years ago
15

How much energy must be transferred out of the system as heat q to lower its temperature to 0∘c? express your answer numerically

in joules?
Physics
1 answer:
serg [7]3 years ago
7 0

Answer:

Incomplete question:

Refer to the temperature versus time graph when answering the questions in Parts C through F. A system consists of 250 of water. The system, originally at = 21.0 , is placed in a freezer, where energy is removed from it in the form of heat at a constant rate. The figure shows how the temperature of the system takes to drop to, after which the water freezes. Once the freezing is complete, the temperature of the resulting ice continues to drop, reaching temperature after an hour. The following specific heat and latent heat values for water may be helpful.

specific heat of ice (at ) = 2.10 J/g K

latent heat of fusion (ice to water phase change at ) = 333.7 J/g

specific heat of water (at ) = 4.186 J/g K

latent heat of vaporization (water to steam phase change at ) = 2256 J/g

specific heat of steam (at ) = 2.01 J/g K

Answers:

Qtotal = 237775 J

Explanation:

To solve this exercise it is necessary to know that if the system is a single phase in which there is a temperature change or if it is a phase change at a single temperature. In the first case, the following formula would be used to calculate the amount of heat:

Q₁ = mCpΔT

Here

m is the mass = 250 g

Cp is the specific heat of ice = 2.1 J/g K

ΔT = 21 - 0 = 21°C = 294 K

In this case the amount of energy is

Q₁ = 250*2.1*294 = 154350 J

In the second case, where there is a phase change at a single temperature, the amount of heat is:

Q₂ = mLf

Here

Lf = latent heat of fusion (ice to water phase change) = 333.7 J/g

Substituting:

Q₂ = 250*333.7 = 83425 J

The total heat is:

Qtotal = 154350+83425=237775 J

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Dennis_Churaev [7]
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I just took this test, and can 100% confirm this is the proper answer.

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6 0
3 years ago
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1.
rusak2 [61]

Answer:

9.6

Explanation:

to convert km to miles multiply by 1.609

7 0
4 years ago
What is the displacement current in the capacitor if the potential difference across the capacitor is increasing at 500
padilas [110]

Answer:

I = 1.21x10^-5 A

Explanation:

You are missing the first part of the problem. This is an example, but it will give you the idea of how to solve yours with your data.

The first part is like this:

<em>A      4.0 cm  diameter parallel plate capacitor has a  0.44 m  m    gap. What is the displacement current in the capacitor if the potential difference across the capacitor is increasing at 500,000 V/s?</em>

Now with this, we can solve the problem.

In order to do this, we need to use the following expression:

q = CV (1)

Where:

C: Capacitance of a parellel capacitor (in Faraday)

q: charge of plate or capacitor (In coulombs)

V: voltage in Volts.

However, we need is the current, and we have data of potential difference, so, all we have to do is divide the expression between time so:

q/t = CV/t

And the current is q/t, thus:

I = C * V/t (2)

And finally, Capacitance C with two plates of area A separated by a distance d is:

C = Eo*A/d (3)

Where:

Eo = constant equals to 8.85x10^-12 F/m.

A = Area of the plate, in this case, πr²

d = gap of the capacitor.

Let's calculate first the Capacitance using equation (3):

C = 8.85x10^-12 * π * (0.04/2)² / 0.00046 = 2.42x10^-11 F

Now, it's time to use equation (2) and solve for I:

I = 2.42x10^-11 * 500,000

I = 1.21x10^-5 A

5 0
3 years ago
A parcel of land is in the shape of an isosceles triangle. The base has a length of 425 ft.; the other sides, which are of equal
kogti [31]

Answer:

The answer to your question is 636.6 ft    

Explanation:

Data

base = 425 ft

angle = 39°

See the picture below

1.- Divide the triangle to get two right triangles.

    Now the superior angle will measure 19.5° and the opposite side will measure 212.5 ft

2.- Use the trigonometric function sine to find the hypotenuse

     sin 19.5 = 212.5/hyp

solve for hyp

    hyp = 212.5 / sin 19.5

Result

    hyp = 212.5/ 0.333

    hyp = 636.6 ft    

4 0
3 years ago
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solniwko [45]

Answer:

glass if for a good view, but for absorbing heat concrete and brick is the best

Explanation:

wood is not a good idea bc it can cause fires from too much heat and it absorbs less heat but all of that depends on how good the material your using

8 0
3 years ago
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