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
Sholpan [36]
3 years ago
10

Consider the electronic elements that are cooled by forced convection in Problem 6.31. The cooling system is designed and tested

at sea level (p ≈ 1 atm), but the circuit board is sold to a customer in Mexico City, with an elevation of 2250 m and atmospheric pressure of 76.5 kPa. (a) Estimate the surface temperature of the chip located 120 mm from the leading edge of the board when the board is operated in Mexico City. The dependence of various thermophysical properties on pressure is noted in Problem 6.19.
Physics
1 answer:
Stella [2.4K]3 years ago
8 0

Answer:

surface temperature of the chip located 120 mm Ts=42.5°C

surface temperature of the chip in Mexico Ts=46.9°C

Explanation:

from the energy balance equation we have to:

q=E=30W

from Newton´s law:

Ts=Tα+(q/(h*A)), where A=l^2

N=h/k=0.04*(Vl/V)^0.85*Pr^1/3

data given:

l=0.12 m

v=10 m/s

k=0.0269 W/(m*K)

Pr=0.703

Replacing:

h=0.04*(0.0269/0.12)*(10*0.12)/((16*69x10^-6))^0.85*(0.703^1/3) = 107 W/m^2*K

The surface temperature at sea level is equal to:

Ts=25+(30x10^-3/107*0.004^2)=42.5°C

h=0.04*(0.0269/0.12)*((10*0.12)/(21*81x10^-6))^0.85*(0.705^1/3)=85.32 W/(m*K)

the surface temperature at Mexico City is equal to:

Ts=25+(30x10^-3/85.32*0.004^2)=46.9°C

You might be interested in
two objects are thrown from the top of a tall building and experience no appreciable air resistance. one is thrown up and the ot
Iteru [2.4K]

Answer:

The two objects are traveling at the same speed.

Explanation:

Neglecting air resistance, an object that is thrown up from the top of a tall building has the same speed as the second object thrown down from the top of the same tall building since the initial speed is the same.

The object thrown up is not traveling faster neither is the object thrown down traveling faster.  

Therefore, the two objects will have the same speed when they hit the ground but their time of landing might be different.

3 0
3 years ago
Read 2 more answers
The term necrosis means
aksik [14]

Necrosis - the death of most or all of the cells in an organ or tissue due to disease, injury, or failure of the blood supply.

Hope this helps, please mark me brainliest

6 0
3 years ago
A thunderstorm loses energy in the _______ stage.
Irina-Kira [14]
 dissipation is the answer ;(
3 0
3 years ago
Read 2 more answers
Which metals can be extracted from following ores (i) Argentite (ii) Haematite (iii) Chalcopyrite (iv) Bauxite​
Sedaia [141]
<h2>Answer </h2>

<h3>1) iron </h3>

<h3>2) Aluminium </h3>

<h3>3) sliver </h3>

<h3>4) copper </h3>

I hope it's helpful for you ☺️

6 0
2 years ago
Read 2 more answers
Ultraviolet light having a wavelength of 97 nm strikes a metallic surface. Electrons leave the surface with speeds up to 3.48 ×
irga5000 [103]

Answer:

<h2><em>12.45eV</em></h2>

Explanation:

Before calculating the work function, we must know the formula for calculating the kinetic energy of an electron. The kinetic energy of an electron is the taken as the difference between incident photon energy and work function of a metal.

Mathematically, KE =  hf - Ф where;

h is the Planck constant

f is the frequency = c/λ

c is the speed of light

λ is the wavelength

Ф is the work function

The formula will become KE =  hc/λ - Ф. Making the work function the subject of the formula we have;

Ф = hc/λ - KE

Ф = hc/λ - 1/2mv²

Given parameters

c = 3*10⁸m/s

λ = 97*10⁻⁹m

velocity of the electron v = 3.48*10⁵m/s

h = 6.62607015 × 10⁻³⁴

m is the mass of the electron = 9.10938356 × 10⁻³¹kg

Substituting the given parameters into the formula Ф = hc/λ - 1/2mv²

Ф =  6.63 × 10⁻³⁴*3*10⁸/97*10⁻⁹ -  1/2*9.11*10⁻³¹(3.48*10⁵)²

Ф = 0.205*10⁻¹⁷ - 4.555*10⁻³¹*12.1104*10¹⁰

Ф = 0.205*10⁻¹⁷ - 55.163*10⁻²¹

Ф = 0.205*10⁻¹⁷ - 0.0055.163*10⁻¹⁷

Ф = 0.1995*10⁻¹⁷Joules

Since 1eV = 1.60218*10⁻¹⁹J

x = 0.1995*10⁻¹⁷Joules

cross multiply

x = 0.1995*10⁻¹⁷/1.60218*10⁻¹⁹

x = 0.1245*10²

x = 12.45eV

<em>Hence the work function of the metal in eV is 12.45eV</em>

6 0
3 years ago
Other questions:
  • A constant voltage of 3.00 V has been observed over a certain time interval across a 3.00 H inductor. The current through the in
    11·1 answer
  • The position of a particle is given by the function x=(5t3−8t2+12)m, where t is in s. at what time does the particle reach its m
    12·2 answers
  • a family backpacking at Yosemite national park took 5 hours to climb a mountain trail 7.5 km long. what was the family's average
    14·1 answer
  • A 20-kilogram mass is traveling with a velocity of 3 m/s. What is the object's kinetic energy?
    12·1 answer
  • The single invention of the ______ has advanced what we know about the universe more than any other scientific technology. a. Su
    9·1 answer
  • A baseball starts from rest and rolls 40.0 m down a hill in 10.0 seconds what is the acceleration
    14·1 answer
  • Convert 1 x 10-3 nm to m. given: 1 m = 1,000,000,000 nm
    8·1 answer
  • Explain what resonance is and give one example of a destructive outcome of resonance. Also give one example of a non-destructive
    9·1 answer
  • A whale comes to the surface to breathe and then dives at an angle 24 degrees to the horizontal surface of the water. The whale
    13·1 answer
  • an interplantetary speedcarft moving at 20000m/s.how far will it travell in one day?(give your answer in km)
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!