What is the simplified meaning of the word "engineering"

Consider the base plate of an 800-W household iron with a thickness of L 5 0.6 cm, base area of A 5 160 cm2, and thermal conduct

N76 [4]

Answer:

a. $\frac{-kdT(0)}{dx} =q_{0}$ =5000W/m^2

b.833.3(0.006-x)+112

c. 117 deg C

Explanation:

Consider the base plate of an 800-W household iron with a thickness of L 5 0.6 cm, base area of A 5 160 cm2, and thermal conductivity of k 5 60 W/m·K. The inner surface of the base plate is subjected to uniform heat flux generated by the resistance heaters inside. When steady operating conditions are reached, the outer surface temperature of the plate is measured to be 112°C. Disregarding any heat loss through the upper part of the iron,

Assumption

Heat conduction is steady state and unidimensional 2. thermal conductivity is constant. Heat supplied is not in the plate

4. we disregard heat loss

Heat flux=heat/area

$\alpha$ /A=800W/160*10^-4

with direction to the surface been in the x direction,

the mathematical expression will be

$\frac{d^2T}{dx^2}$ =0..............1

and $\frac{-kdT(0)}{dx} =q_{0}$ =5000W/m^2

from fourier law, for conductivity

T(L)=T2=112C

b. integrating equation 1 twice we have\dT/dx=c1

T(x)=C1x+C2

C1 and C2 are arbitrary constant

at x=0 the boundary conditions become

-kC1=qo

C1=-(qo/k)

at x=L

=T(L)=C1L+C2=T2

C2=T2-cL1

C2=T2+qoL/k

Juxtaposing C1 and C2 into the general equation , we have

T(x)=-qo/k+T2+qoL/k=qo(L-k)/k+T2

50000*(0.006-x)/60+112

833.3(0.006-x)+112

c. inner surface plate temperature is

T(0)=833.33(0.006-0)+112 ( using the derivation in answer b)

117 deg C

6 0

3 years ago

In an experiment, one selected two samples of copper-silver alloy. One sample has 40 wt% of silver and 60wt% of copper and the o

mote1985 [20]

I belive it’s 3 sorry if it’s wrong

6 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

Select the correct answer.

melomori [17]

Answer:

starburst

Explanation:

There are many different kinds of "hazard symbols," which are being used in order for people to recognize what kind of material they are handling. When it comes to "pictograms," the symbol for a hazard class of explosive is an exploding bomb that shows a starburst effect. An example of such chemical is the "organic peroxide" and other self-reactive chemicals.

A "flame" is a hazard symbol for flammable substances. A "gas cylinder" is a hazard symbol for gases that are located in containers that are under pressure. A "test tube" is a hazard symbol for substances/materials that cause corrosion to skin.

3 0

3 years ago

Technician A says that a special wire brush is needed if it will be rotated at high rpm. Technician B says that some wire brushe

Charra [1.4K]

Answer:

Option C

Both A and B

Explanation:

Both technicians are right about what they say about wire brushes. wire brushes are usually made up of steel wire bristles. however, when high RPMs are involved, it is better to get some special types of brushes for that purpose. This is because the heat generated at high RPMs is great, and most times, damages the brush after prolonged use if it is not specially built for such speeds.

In addition that, some wire brushes have plastic hubs which help support the bristles and is usually attached to the motor.

Considering these, we can say that the Two technicians are right

5 0

4 years ago

What is the simplified meaning of the word "engineering"​

What is the simplified meaning of the word "engineering"