1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
hoa [83]
3 years ago
12

Consider a 1000-W iron whose base plate is made of 0.5-cm-thick aluminum alloy 2024-T6 (rho = 2770 kg/m3 and cp = 875 J/kg·°C).

The base plate has a surface area of 0.03 m2. Initially, the iron is in thermal equilibrium with the ambient air at 22°C. Assuming 90 percent of the heat generated in the resistance wires is transferred to the plate, determine the minimum time needed for the plate temperature to reach 220°C.
Engineering
1 answer:
Lesechka [4]3 years ago
5 0

Answer: 79.98sec

Explanation:

Power received by plate = 0.9x1000

= 900W

Volume of metal = area x thickness

V = 0.5x10^-2 x 0.03 = 1.5x10^-4m3

Mass of metal = density x volume

= 2770kg/m3 x 1.5x10^-4 = 0.4155kg

Electrical heat energy = power x time = mass x specific heat capacity(Cp) x temperature change

900 x t = 0.4155 x 875 x (220-22)

900t = 71985.375

t = 79.98s

You might be interested in
Using the following data, determine the percentage retained, cumulative percentage retained, and percent passing for each sieve.
vekshin1

Solution :

<u>Sieve Size</u> (in)                   <u>Weight retain</u><u>(g)</u>

3                                         1.62

2                                         2.17

$1\frac{1}{2}$                                       3.62

$\frac{3}{4}$                                        2.27

$\frac{3}{8}$                                        1.38

PAN                                    0.21

Given :

Sieve       weight       % wt. retain    % cumulative       % finer

size        retained                               wt. retain

No. 4        59.5            10.225%          10.225%            89.775%

No. 8        86.5            14.865%          25.090%           74.91%

No. 16       138              23.7154%        48.8054%         51.2%

No. 30      127.8           21.91%              70.7154%          29.2850%

No. 50      97               16.6695%         87.3849%         12.62%

No. 100     66.8            11.4796%         98.92%              1.08%

Pan          <u>  6.3    </u>           1.08%              100%                   0%

                581.9 gram

Effective size = percentage finer 10% ($$D_{20})

0.149 mm, N 100, % finer 1.08

0.297, N 50 , % finer 12.62%

x  ,   10%

$y-1.08 = \frac{12.62 - 1.08}{0.297 - 0.149}(x-0.149)$

$(10-1.08) \times \frac{0.297 - 0.149}{12.62 - 1.08}+ 0.149=x$

x = 0.2634 mm

Effective size, $D_{10} = 0.2643 \ mm$

Now, N 16 (1.19 mm)  ,  51.2%

N 8 (2.38 mm)  ,  74.91%

x,  60%

$60-51.2 = \frac{74.91-51.2}{2.38-1.19}(x-1.19)$

x = 1.6317 mm

$\therefore D_{60} = 1.6317 \ mm$

Uniformity co-efficient = $\frac{D_{60}}{D_{10}}$

   $Cu= \frac{1.6317}{0.2643}$

Cu = 6.17

Now, fineness modulus = $\frac{\Sigma \text{\ cumulative retain on all sieve }}{100}$

$=\frac{\Sigma (10.225+25.09+48.8054+70.7165+87.39+98.92+100)}{100}$

= 4.41

which lies between No. 4  and No. 5 sieve [4.76 to 4.00]

So, fineness modulus = 4.38 mm

7 0
3 years ago
Find the remaining trigonometric functions of 0 if
garik1379 [7]

Answer:

cosΘ=−√558

tanΘ=−3√5555

cscΘ=83

secΘ=−8√5555

cotΘ=−√553

8 0
2 years ago
An Otto cycle engine is analyzed using the air standard method. Given the conditions at state 1, compression ratio (r), and pres
My name is Ann [436]

Answer:

A)  222.58 kJ / kg

B)  0.8897 M^3/ kg

c)  0.7737 m^3/kg

D)  746.542 k

E)  536.017 kj/kg

efficiency = 58% ( approximately )

Explanation:

Given Data :

Gas constant (R) =  0.287 kJ/ kg.K

T1 = 310 k

P1 ( Kpa ) = 100

r = 11.5 ( compression ratio )

rp = 1.95 ( pressure ratio )

A ) specific internal energy at state 1

 = Cv*T1 =  0.718 * 310 = 222.58 kJ / kg

B) Relative specific volume at state 1

= P1*V1 = R*T1 ( ideal gas equation )

V1 = R*T1 / P1 = (0.287* 10^3*310 ) / 100 * 10^3

V1 = 88.97 / 100 = 0.8897 M^3/ kg

C ) relative specific volume at state 2

Applying  r ( compression ratio) = V1 / V2

11.5 = 0.8897 / V2

V2 = 0.8897 / 11.5 = 0.7737 m^3/kg

D) The temperature (k) at state 2

since the process is an Isentropic process we will apply the p-v-t relation

\frac{T1}{T2} = (\frac{V1}{V2}^{n-1}  ) = (\frac{P2}{P1} )^{\frac{n-1}{n} }

hence T2 = 9^{1.4-1} * 310 = 2.4082 * 310 = 746.542 k

e) specific internal energy at state 2

= Cv*T2 = 0.718  * 746.542 = 536.017 kj/kg

efficiency = output /input = 390.3511 / 667.5448 ≈ 58%

attached is a free hand diagram of an Otto cycle is attached below

3 0
3 years ago
A large building will need several different types of workmen to install and repair pipes for water, heating,
siniylev [52]

Answer:

Plumber and pipefitters

Explanation:

3 0
3 years ago
Pedro holds a heavy science book over his head for 10 minutes. Petro is doing work during that time. True or False
algol [13]

Answer:

True because he is working his arms to lift and hold the weight

Explanation:

4 0
3 years ago
Other questions:
  • You want to determine whether the race of the defendant has an impact on jury verdicts. You assign participants to watch a trial
    9·1 answer
  • Which tool is used to pull the tapered shaft on a tie-rod end from its mating steering component?
    9·1 answer
  • Plz help me
    12·1 answer
  • Consider a sinusoidal oscillator consisting of an amplifier having a frequency-independent gain A (where A is positive) and a se
    6·1 answer
  • Shear plane angle and shear strain: In an orthogonal cutting operation, the tool has a rake angle = 16°. The chip thickness befo
    7·1 answer
  • Show that -40 F is approximately equal to -40 C.
    12·1 answer
  • A series RC circuit has a voltage of 24VAC and an impedance of 252ohms. What is the circuit current?
    6·1 answer
  • Bob would like to run his house off the grid, therefore he needs to find out how many solar panels and batteries he needs to buy
    12·1 answer
  • IF A CAR AHEAD OF YOU HAS STOPPED AT A CROSSWALK, YOU SHOULD:
    12·1 answer
  • Is the science of measurement
    13·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!