Describe the cycle that purifies drinking water. 40 points

Show that -40 F is approximately equal to -40 C.

V125BC [204]

Answer: Please see below the explanation.

Explanation:

The Celsius (ºC) and Farenheit (ºF), are different temperature scales, but both have identifiable values for two important physical phenomena, water freezing point and water boiling point.

For º C, these are follows:

Freezing Point= 0º C Boiling Point: 100ºC

For º F, we have the following:

Freezing Point= 32º F Boiling Point: 212 ºF

Assuming that all steps (in each scale) between two following values are equal, we have 100 º C between both points in ºC, and 190º in ºF, so degrees in Farenheit are "shorter" than in Celsius, being the relationship, approximately the following:

1 º C = 9/5 ºF.

Taking into account that, by definition, 0ºC = 32º F, we can use the following equations in order to convert ºC to ºF, and viceversa:

ºC = (ºF-32) 5/9

ºF = 32 + 9/5ºC

Now, let's calculate -40ºF, in ºC:

ºC= (-40-32)* 5/9 = -40º C

Let's do the same, converting -40ºC to ºF:

ºF = 32 + (-40)*9/5 = 32 + (-72) = -40ºF.

8 0

3 years ago

Which of the following circumstances call for a greater than normal following distance?

mariarad [96]

Explanation:

The three-second rule is recommended for passenger vehicles during ideal road and weather conditions. Slow down and increase your following distance even more during adverse weather conditions or when visibility is reduced. Also increase your following distance if you are driving a larger vehicle or towing a trailer.

7 0

3 years ago

For a metal casting with a cylindrical riser, what is the best (optimal) aspect ratio (aspect ratio is the ratio of the riser's

DochEvi [55]

Answer:

Optimal aspect ratio = 1

Explanation:

From Chvorinov's Rule,

$T = c [\frac{volume}{surface are}]^n$

Where

T = solidification time

c = mold constant

$Volume = \frac{pi D^2 h}{4}$

$Surface areaA= pi Dh[\frac{2pi D^2}{4}$

For the riser to have the longest solidification time:

We have: D = h

$V = \frac{pi D^3}{4}$

$A = pi Dh[\frac{2pi D^2}{4}] = 1.5D^2 pi$

Therefore,

$\frac{V}{A} = \frac{\frac{pi D^3}{4}}{1.5D^2 pi}$

$\frac{V}{A} = \frac{D}{6}$

To have to longest solidification time, D = h

Therefore the best aspect ratio would be,

$\frac{D}{h} = 1$

3 0

3 years ago

1. (5 pts) An adiabatic steam turbine operating reversibly in a powerplant receives 5 kg/s steam at 3000 kPa, 500 °C. Twenty per

KiRa [710]

Answer:

temperature of first extraction 330.8°C

temperature of second extraction 140.8°C

power output=3168Kw

Explanation:

Hello!

To solve this problem we must use the following steps.

1. We will call 1 the water vapor inlet, 2 the first extraction at 100kPa and 3 the second extraction at 200kPa

2. We use the continuity equation that states that the mass flow that enters must equal the two mass flows that leave

m1=m2+m3

As the problem says, 20% of the flow represents the first extraction for which 5 * 20% = 1kg / s

solving

5=1+m3

m3=4kg/s

3.

we find the enthalpies and temeperatures in each of the states, using thermodynamic tables

Through laboratory tests, thermodynamic tables were developed, these allow to know all the thermodynamic properties of a substance (entropy, enthalpy, pressure, specific volume, internal energy etc ..)

through prior knowledge of two other properties

4.we find the enthalpy and entropy of state 1 using pressure and temperature

h1=Enthalpy(Water;T=T1;P=P1)

h1=3457KJ/kg

s1=Entropy(Water;T=T1;P=P1)

s1=7.234KJ/kg

4.

remembering that it is a reversible process we find the enthalpy and the temperature in the first extraction with the pressure 1000 kPa and the entropy of state 1

h2=Enthalpy(Water;s=s1;P=P2)

h2=3116KJ/kg

T2=Temperature(Water;P=P2;s=s1)

T2=330.8°C

5.we find the enthalpy and the temperature in the second extraction with the pressure 200 kPav y the entropy of state 1

h3=Enthalpy(Water;s=s1;P=P3)

h3=2750KJ/kg

T3=Temperature(Water;P=P3;s=s1)

T3=140.8°C

6.

Finally, to find the power of the turbine, we must use the first law of thermodynamics that states that the energy that enters is the same that must come out.

For this case, the turbine uses a mass flow of 5kg / s until the first extraction, and then uses a mass flow of 4kg / s for the second extraction, taking into account the above we infer the following equation

W=m1(h1-h2)+m3(h2-h3)

W=5(3457-3116)+4(3116-2750)=3168Kw

7 0

3 years ago

Copper is generally considered easy to weld because of its high thermal conductivity: (a) true or (b) false?

inn [45]

Answer:

b)False

Explanation:

Those material have high thermal it is very difficult to weld because due to high thermal conductivity it transmit the heat in to the surrounding and can not reach a particular temperature required to melt the material.And when material does not melt then there is no possibility to weld the material.

So from above we can say that it is very difficult to weld the copper material due to high thermal conductivity.Generally welding of copper done by usiong gas welding technique.

So our option b is right.

8 0

3 years ago