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sattari [20]
2 years ago
15

Water (cp = 4180 J/kg·K) is to be heated by solar-heated hot air (cp = 1010 J/kg·K) in a double-pipe counter-flow heat exchanger

. Air enters the heat exchanger at 90°C at a rate of 0.3 kg/s, while water enters at 22°C at a rate of 0.1 kg/s. The overall heat transfer coefficient based on the inner side of the tube is given as 80 W/m2·K. The length of the tube is 12 m and the internal diameter of the tube is 1.2 cm.
Physics
1 answer:
Inessa [10]2 years ago
3 0

Answer:

452%

Explanation:

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A vertical spring of constant k = 400 N/m hangs at rest. When a 2 kg mass is attached to it, and it is released, the spring exte
Viefleur [7K]

Answer:

4.9 cm

Explanation:

From Hook's Law,

F = ke......................... Equation 1

Where F= force, e = extension, k = spring constant.

Note: the Force acting on the the spring is the weight of the mass.

W = mg.

F = mg.................... Equation 2

Where m = mass, g = acceleration due to gravity

Substitute equation 2 into equation 1

mg = ke

make e the subject of the equation

e = mg/k............... Equation 3.

Given: m = 2 kg, g = 9.8 m/s², k = 400 N/m

e = (2×9.8)/400

e = 19.6/400

e = 0.049 m

e = 4.9 cm

3 0
2 years ago
Charge: A piece of plastic has a net charge of +2.00 μC. How many more protons than electrons does this piece of plastic have? (
snow_lady [41]

Answer

given,

net charge = +2.00 μC

we know,

1 coulomb charge =  6.28 x 10¹⁸electrons

1 micro coulomb  charge =  6.28 x 10¹⁸ x 10⁻⁶ electron

                                         = 6.28 x 10¹² electrons

2.00 μC = 2 x 6.28 x 10¹² electrons

              = 1.256 x 10¹³ electrons

since net charge is positive.

The number of protons should be 1.256 x 10¹³ more than electrons.

hence, +2.00 μC have 1.256 x 10¹³ more protons than electrons.

6 0
2 years ago
A 2 ft x 2 ft x 2 ft box weighs 100 pounds, and the weight is evenly distributed. What is the magnitude of the minimum horizonta
Tems11 [23]

Answer:

Explanation:

Let the force required be F . It is applied at the top of the box . The box is likely to turn about a corner . Torque of this force about this corner

= F x 2

This torque will try to turn the box . On the other hand the weight which is acting at CM will create a torque about the same corner . This torque will try to prevent the box to turn around the corner.

This torque of weight

= 100 x 1

= 100 pound ft.

For equilibrium

Torque of F = torque of weight.

F x 2  = 100

F = 50 pounds .

7 0
2 years ago
Read 2 more answers
An object of mass m has these three forces acting on it (there is no normal force, "no surface"). F1 = 1 N, F2 = 9 N, and F3 = 5
hammer [34]

Answer:

solved

Explanation:

a) F_net = (F2 - F3)i - F1 j

b) |Fnet| = sqrt( (F2 - F3)^2 + F1^2)

= sqrt( (9- 5)^2 + 1^2)

= 4.123 N

c) θ = tan^-1( (Fnet_y/Fnet_x)

= tan^-1( -1/(9-5) )

= -14.036°

7 0
2 years ago
The process of changing a property of a wave to transmit information is called .
BARSIC [14]

Answer : The process of changing a property of a wave to transmit information is called Modulation.

Explanation :

Modulation is the process of changing the property of wave to transmit information. This is done with the help of modulator.

In modulation, the message signal is superimposed on a high frequency signal. A sine wave ( usually high frequency ) is used as a high frequency carrier wave.

Modulation can be done in many ways like :

(1) Frequency modulation

(2) Amplitude modulation

(3) Pulse modulation

8 0
2 years ago
Read 2 more answers
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