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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Holden is trying to determine the velocity of his race car. He went 20 meters east, turned around, and went 40 meters west. He turned the car one more time and went 35 meters east. His car was 15 meters from the starting line. This took 5 seconds.
What is the car’s velocity?
Answer:
3 m/s east
Explanation:
I took a test a got it right
Answer:
3 m/s east
Explanation:
PLS ANSWER ASAP!! I PROMISE I'LL GIVE YOU BRAINLIEST!!
A water-skier is pulled behind a boat by a rope that is at an angle of 13° and has a tension of 490 N. The water-skier has a mass of 49 kg.
What are the magnitudes of the x- and y- components of the tension?
What is the normal force acting on the skier?
Answer:
normal force= 480.2 x component=477.4 y component= 110.4
Explanation:
I'm sorry I just did this today in class but i think normal force has to be equal to mg or the mass * gravity of the person and that would be 480.2 newtons. I multiplied 9.8 (gravity) by the mass of 49g
I think for the x and y components you can make a triangle with the angled string and then use sohcahtoa to solve for the tension. I used cos(13) = x/490 to solve for x component and then I used the pythagoran theroem to get the remaining side which would be : a^2 + 477.4^2 = 490^2
hope this can help and that it is correct. good luck
The magnitudes of the x- and y- components of the tension is 477.44N and 110.23N
The normal force acting on the skier is 480.2N
The magnitude of the x- and y- components of the tension is expressed as:
x = Tcos 13°y = T sin 13°Given the following
Tension T = 490N
x = 490 cos13° = 477.44N
y = 490sin13° = 110.23N
Hence the magnitudes of the x- and y- components of the tension is 477.44N and 110.23N
The normal force acting on the skier is equal to the weight.
N = W = mg
N = W = 49 * 9.8
N = W = 480.2N
Hence the normal force acting on the skier is 480.2N
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What is one characteristic of the convection inside the sun?
- Cells of circulating gasses called granules
- Thick clouds of dust and gasses
- Large cells of rising and sinking gasses
- Nuclear reactions between hydrogen atoms
Answer: 3- Large cells of rising and sinking gasses
Explanation: Hotter gas coming from the radiative zone expands and rises through the convective zone. It can do this because the convective zone is cooler than the radiative zone and therefore less dense. As the gas rises, it cools and begins to sink again. As it falls down to the top of the radiative zone, it heats up and starts to rise. This process repeats, creating convection currents and the visual effect of boiling on the Sun's surface.
A truck drives 80 km in 2 hours. The truck stops for 1 hr and continues driving for 100
km in 2.5 hrs. What was the truck's average speed for the entire trip? (round to the
neared 10th
Answer:
It Crashed Because it was speeding LOL
Explanation:
It was speeding so cops put spices and truck Crashed
Describe the position and velocity of the object based on the motion map.
Answer:
velocity is 1 m/s
Explanation:
Answer:
Include: The object starts away from the origin.
The object moves toward the origin at a constant velocity.
The object stops for one second.
The object moves away from the origin at a greater constant velocity.
Explanation:
When a chocolate bar is a solid does it have low thermal energy?
Answer:
Tiny particles in solids, liquids and gases are always in motion. It is the motion of particles that creates a form of energy called thermal (heat) energy that is present in all matter. The particles in solids are tightly packed and can only vibrate. Matter in its solid state has the lowest amount of thermal energy (for that type of matter). Because solids have less thermal energy than liquids or gasses, the atoms in their solid state move very little.
Explanation:
So yes, chocolate has VERY low thermal energy
HEY CAN ANYONE PLS ANSWER DIS!!!!!!!!
Answer:
Distillation
Explanation:
Answer:
distillation is correct
Explanation:
hope it helps
You testify as an expert witness in a case involving an accident in which car A slid into the rear of car B, which was stopped at a red light along a road headed down a hill (Fig. 6-25). You find that the slope of the hill is u " 12.03, that the cars were separated by distance d " 24.0 m when the driver of car A put the car into a slide (it lacked any automatic anti-brake-lock system), and that the speed of car A at the onset of braking was v0 " 18.0 m/s.With what speed did car A hit car B if the coefficient of kinetic friction was (a) 0.60 (dry road surface) and (b) 0.10 (road surface covered with wet leaves)
Answer:
A) 12.08 m/s
B) 19.39 m/s
Explanation:
A) Down the hill, we will apply Newton’s second law of motion in the downward direction to get:
mg(sinθ) – F_k = ma
Where; F_k is frictional force due to kinetic friction given by the formula;
F_k = (μ_k) × F_n
F_n is normal force given by mgcosθ
Thus;
F_k = μ_k(mg cosθ)
We now have;
mg(sinθ) – μ_k(mg cosθ) = ma
Dividing through by m to get;
g(sinθ) – μ_k(g cosθ) = a
a = 9.8(sin 12.03) - 0.6(9.8 × cos 12.03)
a = -3.71 m/s²
We are told that distance d = 24.0 m and v_o = 18 m/s
Using newton's 3rd equation of motion, we have;
v = √(v_o² + 2ad)
v = √(18² + (2 × -3.71 × 24))
v = 12.08 m/s
B) Now, μ_k = 0.10
Thus;
a = 9.8(sin 12.03) - 0.1(9.8 × cos 12.03)
a = 1.08 m/s²
Using newton's 3rd equation of motion, we have;
v = √(v_o + 2ad)
v = √(18² + (2 × 1.08 × 24))
v = 19.39 m/s
What happens to the temperature of a substance while it is changing state?
A. It increases first and then decreases.
B. It decreases first and then remains constant.
C. It varies randomly.
D. It remains constant.
Answer:
During a phase change, the temperature will remain constant. Obviously all the heat is used in phase transformation. So the correct answer should be D. Forgive me if I'm wrong but I hope this helps!
The temperature of a substance remains constant while it is changing state. Thus, the correct option is D.
What is the relation between state and temperature of substance?Temperature has a direct effect on whether a substance exists in states as a solid, liquid, or gaseous substance. Substances can change their phase often because of a temperature change of the substance. At very low temperature conditions, most of the substances are solid, as the temperature of the substance keeps on increasing, then they become liquid and at very higher temperatures still, they become gaseous substances.
The temperature of a substance remains constant while it is changing its state.
Therefore, the correct option is D.
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Help, please
and explain
a car on a circular track accelerates from rest. the radius of the track is 0.30km and the magnitude of the constant angular acceleration is 4.5x10-3 rads/s squared. find the centripetal acceleration of the car when it has completed half of a lap.
Answer:
The centripetal acceleration of the car is 50.4 m/s²
Explanation:
Given;
radius of the track, r = 0.3km = 300 m
constant angular acceleration, α = 4.5 x 10⁻³ rad/s²
during half of a lap, θ = π
Determine time of motion
θ = ωt + ¹/₂αt²
π = 0 + ¹/₂αt²
t² = 2π / α
t² = ( 2 x 3.142) / (4.5 x 10⁻³)
t² = 1396.44
t = √1396.44
t = 37.369 s
Determine the angular velocity
[tex]\omega_f = \omega_i + \alpha t\\\\\omega_f = 0 \ + \ 37.369*4.5*10^{-3}\\\\\omega_f = 0.168 \ rad/s[/tex]
Determine the centripetal acceleration of the car
[tex]\alpha _c = \omega^2 r\\\\\alpha _c = 0.168*300\\\\\alpha _c =50.4 \ m/s^2[/tex]
Therefore, the centripetal acceleration of the car is 50.4 m/s²
How does using a ramp make work easier when loading a piano onto a truck three feet above the ground?
It allows a larger force to be applied over a shorter distance.
It allows a larger force to be applied over a longer distance.
It allows a smaller force to be applied over a shorter distance.
It allows a smaller force to be applied over a longer distance.
Answer:
It allows a smaller force to be applied over a longer distance.
Explanation:
A ramp is an example of an inclined plane that makes the movement of object easier above the ground level or higher surfaces.
In the given example, the sloping part of the ramp will support the weight of the piano as it moves up the slope and it will allow less force to be applied to move the piano above but the distance would be longer as the slant length or slope is the longest distance.
Hence, the correct answer is "d".
Answer:
D. It allows a smaller force to be applied over a longer distance.
Explanation:
What is the speed of a car that moves 400 feet in 4 seconds?
Answer:
272.727mph(miles per hour)
Explanation:
How does the earthquake magnitude work
Answer:
The magnitude of an earthquake is determined from the logarithm of the amplitude of waves recorded by seismographs. Adjustments are included in the magnitude formula to compensate for the variation in the distance between the various seismographs and the epicenter of the earthquakes.
Explanation:
have a good day
what would you want the after life to be like. examples are heaven and hell ,reincarnation ,eternal darkness , reliving your live but different choices or become a ghost,
Answer:
i would want to be a dog or a cat
Explanation:
there just funny
what is an ammeter used for ?How can it be connected to make a measurement for a circuit component
Answer:
See the explanation below.
Explanation:
An ammeter is an instrument for measuring electrical currents in a circuit. To measure the current the ammeter must be connected in series with the circuit so that the current flows through it. At present time there are modern instruments such as the amperimetric clamp, which also serves to measure currents in a more easy way
Which of the following substance used to selectively absorb certain frequencies of light and transmit or reflect the rest; responsible for object's colour?
A. Reflection
B. Refraction
C. Pigment
D. Tyndall scattering
Answer:
[tex]D. \: Tyndall \: scattering.[/tex]
PLZZZ
suppose you increase the voltage in the coils of the solenoid of an electromagnet. what happens the the electromagnet?
A. its strength becomes less
B. its strength decreases then increases
C. its strength becomes greater
D. its strength remains the same
Answer:
Its strength becomes greater
Explanation:
Suppose you increase the voltage in the coils of the solenoid of an electromagnet. the electromagnet strength becomes greater. Hence option C is correct.
What is Electromagnet ?An electromagnet is a type of magnet where an electric current creates the magnetic field. The wire that makes up an electromagnet is often twisted into a coil. A magnetic field is produced by a current flowing through the wire and is focused in the hole in the centre of the coil. When the current is cut off, the magnetic field vanishes. In order to create a stronger magnet, the turns of the wire are frequently twisted around a magnetic core composed of a ferromagnetic or ferrimagnetic material, such as iron.
An electromagnet's key benefit over a permanent magnet is the ability to swiftly alter the magnetic field by adjusting the amount of electric current flowing through the winding. Contrary to a permanent magnet, however
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What is the pressure on a surface when a 20 N force is applied 10 m2, 5 m2, 2 m2
16. Evaluate the expression below if
a = -8, b = 17, and c = 21
az - (b + c)
Answer:
(if for solving for z)
z= -4.75
Explanation:
az-(b+c) [set equal to zero]
az-(b+c)=0
+(b+c) +(b+c)
az = (b+c) [now substitute the variables]
-8z = (17+21)
-8z = 38 [divide both sides by -8 to get z alone]
z = -4.75
what does the slope of the line represent on a velocity vs time graph
Answer:
The principle is that the slope of the line on a velocity-time graph reveals useful information about the acceleration of the object. If the acceleration is zero, then the slope is zero. If the acceleration is positive, then the slope is positive
Explanation:
What do x-direction and y-direction refer to when discussing an object's motion
Answer:
The x-direction and y-direction refer are used to refer to the location of an object as well as to the components of the motion of the object in a two dimensional space
Explanation:
In physics, in the analysis of the motion of an object in two dimensional space, the relative location of the object is specified using the measured distances in the x-direction from the y-axes and y-direction from the x-axes
In order to accurately specify the motion of the object, information regarding the component of the motion of the object in the x-direction and the component in the y-direction are required
what is the acceleration of an object that entered of a force 200 N if the object mass was 100 kg?
Answer:
The answer is 2 m/s²Explanation:
The acceleration of an object given it's mass and the force acting on it can be found by using the formula
[tex]a = \frac{f}{m} \\ [/tex]
where
f is the force
m is the mass
From the question we have
[tex]a = \frac{200}{100} \\ [/tex]
We have the final answer as
2 m/s²Hope this helps you
What is the net force required to accelerate a 5.3 kg box at a rate of 4.2 m/s^2?
Answer:
The answer is 22.26 NExplanation:
The force acting on an object given the mass and acceleration we use the formula
force = mass × accelerationFrom the question
mass = 5.3 kg
acceleration = 4.2 m/s²
We have
force = 5.3 × 4.2
We have the final answer as
22.26 NHope this helps you
Why are ions formed?
Group of answer choices
A.Because atoms have the same number of protons and electrons
B. Because atoms want 8 valence electrons
C. To make our lives difficult
D. Because atoms gained neutrons
Answer:
B. Because atoms want 8 valence electrons
Explanation:
Ions are formed because atoms want 8 valence electrons. Most atoms attain stability when they 8 electrons in their outermost shell.
This is the reason why they form ions.
To form ions, atoms will gain or lose electrons or share them. This loss, gain, or sharing of electrons often lead to an atom become stable. One group of atoms, the noble gases, do not form ions readilyThey have complete numbers of electrons in their valence shells. So they do not gain, lose or share their electrons to form ions unlike the others.A man jumps from a 45 m cliff into a large body of water. How long will he fall before he enters the wate
Answer:
about 2.5 seconds depending on if he jumps up and out or if he jumps out.
Explanation:
One frequent sign of gender inequality in the United States is that women do not ___________. A. enjoy the same voting rights as men B. earn as much as men in similar occupations C. receive admission to college as much as men D. have equal power in most relationships
One frequent sign of gender inequality in the United States is that women do not earn as much as men in similar occupation. So, option (B) is correct.
What is gender inequality?Men and women are not treated equally in society, which social problem is referred to as gender inequality. Distinctions in genetics, psychology, or prevailing cultural norms in the society may be the cause of the treatment. While some of these distinctions are based on scientific research, others seem to be social constructs.
Numerous areas of study, such as education, life expectancy, personality, interests, family life, careers, and political affiliation, demonstrate the differences in gender experiences. Gender inequality impacts non-binary people and is experienced differently across cultural boundaries.
In the United States, One frequent sign of gender inequality is that women do not earn as much as men in similar occupations. So, option (B) is correct.
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Answer:
B
Explanation:
edge2020
Steve stands on a scale and it reads 65 kilograms. What is his weight in Newtons? *
Need help
Answer:
It would be 637.43 Newtons
Explanation:
Because
1 Kilogram:
The kilogram is defined as being equal to the mass of the International Prototype Kilogram (IPK), which is almost exactly equal to the mass of one liter of water.
1 Newton:
1 Newton in Earth gravity is the equivalent weight of 1/9.80665 kg on Earth. This is derived using Newton's second law f=ma and assuming Earth gravity of 9.80665 m/s2. 1 N (Earth) = 0.101971621297793 kg.
How much work is done by a person who used a force of 27.5N to move a grocery cart 12.3
Answer:
workdone = force x displacement
= 27.5 x 12.3
= 338.25 J
A Force Of 15 N Is Applied To A Spring, Causing It To Stretch 0.3 M. What Is The Spring Constant For The Particular Spring
Answer:
50 on edge
Explanation: