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Novosadov [1.4K]
3 years ago
5

An air conditioner running with R-134a on a cycle executed under the saturationdome between the pressure limits of 0.8 MPa and 0

.12 MPa. Calculate themaximum Coefficient of Performance of this heat pump.
Physics
1 answer:
ohaa [14]3 years ago
8 0

Answer:

The COP of the system is = 4.6

Explanation:

Given data

Higher pressure  = 1.8 M pa

Lower pressure = 0.12 M pa

Now we have to find out high & ow temperatures at these pressure limits.

Higher temperature corresponding to pressure 1.8 M pa

T_{H} = 62.9 °c = 335.9 K

Lower temperature corresponding to pressure 0.2 M pa

T_{L} = - 10.1 °c = 262.9 K

COP of the system is given by

COP = \frac{T_{L} }{T_{H} -T_{L}   }

COP = \frac{335.9}{335.9 -262.9}

COP = 4.6

Therefore the COP of the system is = 4.6

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A hollow plastic sphere is held below the surface of a fresh-water lake by a cord anchored to the bottom of the lake. The sphere
Naya [18.7K]

Answer: a) B = 6811N

              b) m = 603.2kg

              c) 86.8%

Explanation: <em>Buoyant force</em> is a force a fluid exerts on a submerged object.

It can be calculated as:

B=\rho_{fluid}.V_{obj}.g

where:

\rho_{fluid} is density of the fluid the object is in;

V_{obj} is volume of the object;

g is acceleration due to gravity, is constant and equals 9.8m/s²

a) For the hollow plastic sphere, density of water is 1000kg/m³:

B=10^{3}.0.695.9.8

B = 6811N

b) Anchored to the bottom, the forces acting on the sphere are <u>Buoyant</u>, <u>Tension</u> and <u>Force due to gravity</u>:

B = T + F_{g}

B = T + mg

mg = B - T

m=\frac{B - T}{g}

Calculating:

m=\frac{6811 - 900}{9.8}

m = 603.2kg

c) When the shpere comes to rest on the surface of the water, there are only <u>buoyant</u> <u>and</u> <u>gravity</u> acting on it:

B = m.g

\rho_{w}.V_{sub}.g=m.g

V_{sub}=\frac{m}{\rho_{w}}

V_{sub}=\frac{603.2}{1000}

V_{sub} = 0.6032m³

Fraction of the submerged volume is:

\frac{V_{sub}}{V_{obj}} = \frac{0.6932}{0.695} = 0.868

<u />

3 0
3 years ago
Which of these circuit schematics has an ammeter?<br> Α. Α<br> B. B<br> C. C<br> D. D
madam [21]

Answer:

d is the correct answer for this question hope it helps

Explanation:

when you see a A in a circle the the ammeter

3 0
3 years ago
Read 2 more answers
Melissa uses bags of mulch that way 40 pounds each. She needs to carry 10 bags to her truck. She usually carries one bag at a ti
arsen [322]
No. She would be doing the same amount of work that way. Work is defined to be equal to the force multiplied by the distance. Carrying two bags at a time would cause her to exert twice the effort, so the total amount of work done in the end would still be the same.
4 0
3 years ago
Write some harms of friction.
Veseljchak [2.6K]

Answer:

Friction produces unnecessary heat leading to the wastage of energy. The force of friction acts in the opposite direction of motion, so friction slows down the motion of moving objects. Forest fires are caused due to the friction between tree branches. However, friction can also cause problems in a car. Friction between moving engine parts increases their temperature and causes the parts to wear down. Friction can be both harmful and helpful, so it may be necessary to decrease or increase friction.

3 0
3 years ago
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You drive a car 1600 ft to the east, then 2500 ft to the north. The trip took 2.5 minutes. What was the magnitude of your averag
elena-14-01-66 [18.8K]

Answer:

Velocity=6.03m/s

Explanation:

Given data

Time t=2.5 minutes=150 seconds

Distance A=1600 ft=487.68 m........east

Distance B=2500 ft=762m ........north

To find

Average velocity

Solution

First we need to find the resultant distance magnitude.To find that we apply Pythagorean theorem to find hypotenuse

So

A^{2}+B^{2}=C^{2}\\  C=\sqrt{A^{2}+B^{2}}\\ C=\sqrt{(487.68m)^{2}+(762m)^{2}}\\ C=904.7m

Velocity=\frac{Distance}{Time}\\Velocity=\frac{904.7m}{150s}\\Velocity=6.03m/s

7 0
3 years ago
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