Answer:
a. 0.122 ft b. -70 Btu/h ft² c. 633.33 °F
Explanation:
a. Since the rate of heat loss dQ/dt = kAΔT/d where k = thermal conductivity, A = area, ΔT = temperature gradient and d = thickness of insulation.
Now [dQ/dt]/A = kΔT/d
Given that [dQ/dt]/A = rate of heat loss per unit area = -900Btu/h ft², k = 0.10 Btu/h ft ℉(for asbestos), ΔT = T₂ - T₁ = 500 °F - 1600 °F = -1100 °F. We need to find the thickness of asbestos, d. So,
d = kΔT/[dQ/dt]/A
d = 0.10 Btu/h ft ℉ × -1100 °F/-900Btu/h ft²
d = 0.122 ft
b. If the 3 in thick Kaolin is added to the outside of the asbestos, and the outside temperature of the asbestos is 250℉, the heat loss due to the Kaolin is thus
[dQ/dt]/A = k'ΔT'/d'
k' = 0.07 Btu/h ft ℉(for Kaolin), ΔT' = T₂ - T₁ = 250 °F - 500 °F = -250 °F and d' = 3 in = 3/12 ft = 0.25 ft
[dQ/dt]/A = 0.07 Btu/h ft ℉ × -250 °F/0.25 ft
[dQ/dt]/A = -70 Btu/h ft²
c. To find the temperature at the interface, the total heat flux equals the individual heat loss from the asbestos and kaolin. So
[dQ/dt]/A = k(T₂ - T₁)/d + k'(T₃ - T₂)/d' where [dQ/dt]/A = -900Btu/h ft², k = 0.10 Btu/h ft ℉(for asbestos), k' = 0.07 Btu/h ft ℉(for Kaolin), T₁ = 1600 °F, T₂ = unknown and T₃ = 250℉.
Substituting these values into the equation, we have
-900Btu/h ft² = 0.10 Btu/h ft ℉(T₂ - 1600 °F)/0.122 ft + 0.07 Btu/h ft ℉(250℉ - T₂)/0.25 ft
-900Btu/h ft² = 0.82 Btu/h ft ℉(T₂ - 1600 °F) + 0.28Btu/h ft ℉(250℉ - T₂)
-900 °F = 0.82(T₂ - 1600 °F) + 0.28(250℉ - T₂)
-900 °F = 0.82T₂ - 1312°F + 70 °F - 0.28T₂
collecting like terms, we have
-900 °F + 1312°F - 70 °F = 0.82T₂ - 0.28T₂
342 °F = 0.54T₂
Dividing both sides by 0.54, we have
T₂ = 342 °F/0.54
T₂ = 633.33 °F
The thickness of asbestos required is 0.122 ft.
The heat flux will be -70 Btu/h ft²
And the temperature of the interface is 633.33 °F.
(i) the rate of heat loss :
dQ/dt = kAΔT/d
where k = thermal conductivity, A = area, ΔT = temperature gradient, and
d = thickness of insulation.
[dQ/dt]/A = kΔT/d
Given that [dQ/dt]/A = rate of heat loss per unit area = -900Btu/h ft²,
k = 0.10 Btu/h ft ℉,
ΔT = 500 °F - 1600 °F = -1100 °F
We have to find the thickness of asbestos that is d.
d = kΔT/[dQ/dt]/A
d = 0.10 Btu/h ft ℉ × -1100 °F/-900Btu/h ft²
d = 0.122 ft is the thickness required.
(ii) a 3-in thick Kaolin is added to the outside of the asbestos
outside temperature of the asbestos is 250℉,
the heat loss due to the Kaolin is:
[dQ/dt]/A = k'ΔT'/d'
k' = 0.07 Btu/h ft ℉(for Kaolin), ΔT' = T₂ - T₁ = 250 °F - 500 °F = -250 °F and d' = 3 in = 3/12 ft = 0.25 ft
[dQ/dt]/A = 0.07 Btu/h ft ℉ × -250 °F/0.25 ft
[dQ/dt]/A = -70 Btu/h ft²
(iii) temperature at the interface
the total heat flux :
[dQ/dt]/A = k(T₂ - T₁)/d + k'(T₃ - T₂)/d'
where [dQ/dt]/A = -900 Btu/h ft²,
k = 0.10 Btu/h ft ℉ (for asbestos),
k' = 0.07 Btu/h ft ℉ (for Kaolin),
T₁ = 1600 °F and T₃ = 250℉.
-900 = 0.10(T₂ - 1600 °F)/0.122 + 0.07(250℉ - T₂)/0.25
-900 = 0.82(T₂ - 1600 °F) + 0.28(250℉ - T₂)
-900 °F = 0.82(T₂ - 1600 °F) + 0.28(250℉ - T₂)
-900 °F = 0.82T₂ - 1312°F + 70 °F - 0.28T₂
-900 °F + 1312°F - 70 °F = 0.82T₂ - 0.28T₂
342 °F = 0.54T₂
Dividing both sides by 0.54, we have
T₂ = 342 °F/0.54
T₂ = 633.33 °F
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a spring balance used to weigh candy is built with a spring the spring stretches 3.00 cm when a 15 n weight is placed in the pan. when the weight is replaced with 3 kg of candy, what distance will the spring stretch?
a.7.0 b.4.5 c.3.8 d.5.9
Answer: 5.9cm
Explanation:
15N/3cm=5
Convert 3kg to N (29.42N)
Use the 5 from earlier to divide 29.42/5=5.884
Round to 5.9
5.9cm is the answer
(I don’t know if I solved this the correct way but I got it right. 5.9 is the correct answer)
The upward force on a car that is falling off a cliff is what?
a. air resistance
b. momentum
c. inertia
d. terminal velocity
Answer:
A. air resistance
Explanation:
I think so
Calculate the Velocity.
What is the average velocity of a car that moved 60km in 3 hours?
O A: 10 km/h
B: 20 km/h
C: 30 km/h
D: 60 km/h
The car's average speed is 20 km/hr.
There's not enough information given to calculate its velocity.
A bus travels 6 km east and then 8 km south. The magnitude of the bus’s resultant displacement is ___km.
I would like an explanation as well so I know how you got the answer you got.
Answer:
10 km
Explanation:
You can draw your problem out. You can use the pathagoran theorem to figure it out. So [tex]6^{2}[/tex] + [tex]8^{2}[/tex] and then square root the answer which will be [tex]\sqrt{100}[/tex] which equals to 10.
Are noble gases nonreactive elements?
Answer:
Noble gases are nonreactive elements.
Explanation:
We call Group 18 of the Periodic Table "Noble gases" because they are inert gases. They do not like to bond with other elements.
The reason why is because their outermost shell for electrons is full. These electrons, called valence electrons, are are completely maxed out and therefore makes the element stable. This in turn makes it so that it doesn't really bond with other elements.
Answer:
Yes. Noble gases ARE nonreactive elements.
Explanation:
If a rock is skipped into a lake at 24 m/s2 with what force as the rock
thrown if it was '1,75 kg?
Answer:
Force = Mass * Acceleration
Explanation:
24*1.74= 42 N
An object that has 0 acceleration will never be in motion
Answer:
False
Explanation:
HEY CAN ANYONE PLS ANSWER DIS!!!!!!!
Answer:
A. Filtration
Explanation:
Chromatography can not be used to seperate A(l) from the mixture. And you can not even perform the method since B(s) is present.
As for distillation, this process is used to seperate liquid from mixture of liquids. Filtration is effective in seperation of liquid and solid.
Which unit you would use to measure the following objects? This is so confusing
Answer:
weight of truck in kg, height of person in meter m, amount of water in kiloliter kl, length of eyelash in mm
Two technicians are discussing the FMVSS 135 standards for parking brakes. Technician A states that the hand force required to set the brake should not exceed 80 lb. Technician B states that the foot force to set the brake should not exceed 80 lb. Which technician is correct?
Answer:
Technician A
Explanation:
Technician A is correct because, the hand force required is not supposed and even should not exceed 80 lb.
On the other hand, the foot force limit is even higher at 100 lb. Thus, the required foot force break should not exceed 100 lb. We are given 80 lb in the question, which is quite less than 100 lb. It could exceed 80, but must not exceed 100. Thus only Technician A is correct among them both.
Which of the following offers guidance to individuals in various situations of conflict, confusion and crisis by means of providing tools necessary for self-development?
Answer:
confusion
Explanation:
mark as brainlist plz
The part of a flower which holds the egg cells is the:
ovary
style
stamen
anther
Answer:
Maybe pistil or ovary
pistil usually is located in the center of the flower and is made up of three parts: the stigma, style, and ovary
Answer:
A. Ovary
Explanation:
What layer of atmosphere does planes fly?
Answer: stratosphere
The stratosphere is the second to last layer of atmosphere to the Earth. It is about 40,000 feet above, and this is the range where planes fly. So, the answer is stratosphere.
Hope this helps!
Answer:
stratosphere
Explanation:
Planes fly in the stratosphere of the atmosphere.
The answer to the question is stratosphere.
Okay? Thank you so much for 25 points.
What is the velocity of a plane that took 2 hours to travel 1000 miles north?
A. 500 miles per hour North
B. 500 miles
C. 500 miles North
D. 500 miles per hour
The convection currents in the asthenosphere cause the movement of the
Can someone help me please, thanks.
Answer:
rotation
Explanation:
Im pretty sure. Please heart and mark brainliest
Answer:
cycle
Explanation:
either rotation or cycle. I would think.
all known frequencies of the visible spectrum are..
a. solar light
b. light
c. black light
Explanation:
[tex]b. \: light[/tex]
Mr. Chang's class participated in a science experiment where they placed three substances outside in the sunlight to determine which substance would increase in temperature more quickly. How would the motion of the particles of each substance be described if they are allowed to sit in the Sun for a duration of 10 minutes?
Choices:
The particles do not change in motion because the substances are undisturbed.
The particles of each substance begin to speed up and move farther apart as the temperature increases.
The particles of each substance begin to slow down and move closer together as the temperature increases.
The particles of each substance speed up and slow down simultaneously, but remain in a fixed position as the temperature increases
Answer:
B or D but im pretty sure it is D
Explanation:
When molecules are left in the sun, it heats up. When molecules heat up, the begin to vibrate rapidly. The sun is not constant as it could get blocked by clouds, so it would, at times, slow down the movement of the molecules. The answer is most likely D.
free brainlist but you have to get this right
100000000000000000000 times 200000000000000 times 3000000000000000 times 1 times 200000000000000000000000000000 times 5
You Can Use Caculator
Answer:
the answer is 6e+79
Answer:
yea the answer is 6e+79 i did use a couculater though
Explanation:
What are the two parts of an atom? the nucleus and the proton coud the neutron and the electron the neutron and the proton cloud the nucleus and the second 00
Answer: The Nucleus and the Electrons are the 2 Parts of the atom.
Explanation:
Which answer explains why plate B is moving underneath plate A
A. Plate B is more dense than plate A because it is composed of oceanic crust
B. Plate A is more dense than plate B because it is composed of oceanic crust
C. plate B is more dense than plate A because it is composed of continental crust
D. Plate A is more dense than plate B because it is composed of continental crust
Answer:
A.
Explanation:
Earth is composed of different layers and one layer moves over another due to differences in the densities.
According to the physics of density, a substance having less density floats over a higher density substance. The oceanic crust has more density than the continental crust that is why continental crust float over oceanic crust.
So in the given example, plate B is moving below the plate A, it means plate B is more dense than plate A because plate B is composed of oceanic crust . For example : continents float over the asthenosphere (a layer below the lithosphere).
Hence, the correct answer is "A ".
if your mass is 72kg your textbooks in Madison has 3.7 kg and you and your textbook are separated by a distance of 0.33 M what is the gravitational force between you and your textbook
Answer:
1.63 X 10^-7N
Explanation:
how long would it take for a car to travel 200 km if it has an average speed of 55 km/hr?
Answer:
3.6
Explanation:
Answer:
3.64 hrs
Explanation:
what are 3 sources of heat inside earth?
1. Heat from when Earth was formed.
2. Frictional Heat, which is caused by heavier core material sinking to the center of the Earth.
3. Heat from the decay of elements that are radioactive.
Urgent and easy
Give an example where the following energy changes would take place:
7) Electrical to Thermal-
8) Chemical to Thermal-
9) Electrical to Mechanical-
10) Radiant to Chemical-
Answer:
7) Oven, toaster. 8) Fire, gas stove. 9) Television? No.. umm.. generator, yeah a generator 10) photosynthesis
Explanation:
What does hydrosphere and cryosphere both have in common?
Answer:
cryosphere is all those areas of earth where the surface is frozen while hydrosphere is all waters of earth, as distinguished from the land and the gasses of the atmosphere
write any three rules two keep in in mind while using SI units
Answer:
Rules and conventions for writing SI units and their symbols
The units named after scientists are not written with a capital initial letter. ...
The symbols of the units named after scientist should be written by a capital letter. ...
Small letters are used as symbols for units not derived from a proper name
Explanation:
Hope this helps u
Crown me as brainliest:)
Answer:
when temperature is expressed in Kelvin,the degree sign is omitted.
only accepted symbols should be used.
some space is always to be left between the number and the symbol of the unit and also between the symbols for compound units such as force,momentum, etc.
What collides and creates a movement of heat called conduction?
A. photons
B. compounds
C. Molecules
D. atoms
Answer:
c.
Explanation:
Molecules collide and create a movement of heat called conduction.
What is conduction?
Conduction is defined as a process as a means of which heat is transferred from the hotter end of the body to it's cooler end.Heat flows spontaneously from a body which is hot to a body which is cold.
In the process of conduction,heat flow is within the body and through itself.In solids the conduction of heat is due to the vibrations and collisions of molecules while in liquids and gases it is due to the random motion of the molecules ,
When conduction takes place, heat is usually transferred from one molecule to another as they are in direct contact with each other.There are 2 types of conduction:1) steady state conduction 2) transient conduction.According to the type of energy conduction is of three types:
1) heat conduction
2) electrical conduction
3)sound conduction
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#SPJ2
An air bubble is at a depth of 3 m below
the surface of lake. What is the pressure
of water on the air bubble?
(take density of water = 1000 kgm )
Answer:
incorrect its 987 for exact
How do you find the surface area of a rectangular object?
Answer:
A=2(wl+hl+hw)
Explanation:
Hope this helps! :)