Answer:
t= 4.5s
Explanation:
vi=0m/s
a= 1m/s
d=10m
10m= 0(t) + 1/2(1m/s)(t^2). 0xt cancels out, 1/2 of 1= .5
10m= .5m/s(t^2) Divide both sides by .5
20m= t^2. Take square root of each side
Square root of 20 is 4.472135954999579
sig figs, t= 4.5 s
The heat loss from a boiler is to be held at a maximum of 900Btu/h ft2 of wall area. What thickness of asbestos (k= 0.10 Btu/h ft ℉) is required if the inner and outer surfaces of the insulation are to be 1600 and 500℉, respectively? Now if a 3-in.-thick layer of kaolin brick (k= 0.07 Btu/h ft ℉) is added to the outside of the asbestos, what heat flux will be result if the outside surface of the kaolin is 250℉? What will be the temperature at the interface between the asbestos and kaolin for this condition?
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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You are designing an apparatus to shoot a water balloon through a 3rd story window (25m above the ground)
Answer:
The balloon needs a vertical velocity of approximately 22.14 m/s to reach the window
Explanation:
The given parameters are;
The destination of the designed water balloon we shoot = The 3rd story window
The height of the 3rd story window which the water balloon should reach = 25 m
Therefore, we have, the equation of motion of the water balloon given as follows;
v² = u² - 2 × g × s
Where;
[tex]u_y[/tex] = The initial vertical velocity of the balloon
[tex]v_y[/tex] = The final vertical velocity of the balloon = 0 m/s
g = The acceleration due to gravity = 9.8 m/s
s = The height the balloon is intended reach at the final velocity becomes 0 m/s = The height of the 3rd story window
∴ s = 25 m
Substituting the values, we have;
0² = [tex]u_y[/tex]² - 2 × 9.8 × 25
[tex]u_y[/tex]² = 2 × 9.8 × 25 = 490
[tex]u_y[/tex] = √490 = 7·√10
The initial vertical velocity of the balloon = [tex]u_y[/tex] = 7·√10 m/s
Therefore, the balloon needs a vertical velocity of 7·√10 m/s which is approximately 22.14 m/s to reach the window.
What was the instantaneous speed of Bear A at 5 seconds in meters/min? (No unit conversions necessary, no units required for answer).
Answer:
Answer: The answer is 40.
Explanation: There is a typo, they mean 5 minutes. Five minutes is the line between zero and 10, and the dot matches up at 5 and 200. 200 divided by 5= 40.
(i got this answer from: https://brainly.com/question/18253554)
How do you find the surface area of a rectangular object?
Answer:
A=2(wl+hl+hw)
Explanation:
Hope this helps! :)
Which of the following statements is accurate when considering the role of cognition in shaping behavior? A. Cognition helps determine if a consequence is influential enough to control behavior. B. Cognition will most likely decrease the chance for classical conditioning to work. C. One’s cognitive processes are irrelevant when it comes to shaping behavior. D. One’s cognitive processes only work in shaping behavior when a particular consequence is desired. Please select the best answer from the choices provided A B C D
Answer: the answer is A.
Explanation:
brainliest please?
Answer:
A.
Cognition helps determine if a consequence is influential enough to control behavior.
Explanation:
This is right on edg. 2020
The mass of an object is 200 kg. What is it's weight on Earth
Answer:
1N=1 kg×m/s (sqaured)
Explanation:
basically if you are 225 lb u weigh 1000N. I hope I helped
Hydrogen is found as a gas on Earth but exists in all four states in the solar
system. Four samples of hydrogen have equal masses but are each in a
different state. Which statement about the relative amounts of thermal
energy in the samples is true?
Answer: the sample of solid has less energy than the sample of gas
Explanation:
APEX
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:
a standby generator is connected to fifteen 40w and a musical 600w amplifying system. how many energy is used up if the generator run 6hours
pls someone answer the question fast
Answer:
1200 watts
-hope this helps
Why is thermal energy classified as kinetic energy?
Answer:
Thermal energy is an example of kinetic energy, as it is due to the motion of particles, with motion being the key. Thermal energy results in an object or a system having a temperature that can be measured. Thermal energy can be transferred from one object or system to another in the form of heat.
Explanation:
Answer:
Thermal energy is an example of kinetic energy, as it is due to the motion of particles, with motion being the key. Thermal energy results in an object or a system having a temperature that can be measured. Thermal energy can be transferred from one object or system to another in the form of heat.
Explanation:
It takes 39.7 N to push a crate at a constant speed across flat ground where μk=0.438 what is the mass of the crate
Answer:
I don't know how to show the work but I just had this question and the answer is 9.24kg.
Explanation:
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:
5. A book is placed on a table. If the book exerts a force of 15 N'on the table,
how much force does the table exert on the book?
A. ON
C. 9.8 N
B. 3 N
D. 15 N
Answer:
D
Explanation:
The table is NOT in motion, so it will remain still. Newton's second law states that for every action, there's an equal and opposite reaction. Therefore, the table must push back the opposite direction(up) with the same force(15N)
The reverse of the process of sublimation is called
a freezing.
b vaporization.
c deposition.
d condensation.
Science
Using the graphs on your notes, how are wavelength and frequency related to sound waves? Make sure to use proper terminology in your response.
tony walks at an average speed of 70m/min from home to school. If the difference between his home and the school is 2100 m, how much time does it take for Tony to walk to school?
Where does the focal point of a convex mirror fall?
a. In front of the mirror.
b. Behind the curvature of the mirror.
C. At the vertex.
d. None of the above.
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.
In february a little town received snow on a daily basis. The first day they had 10 inches, 3 inches the second, 7 inches the 3rd, and 4 inches on the fourth day. What was the average snowfall?
Answer:
The average is 6
Explanation:
To find the average, you have to first add all the numbers. After you add all the numbers up, then you divide by how many numbers there are. This one had 4 numbers so you divide by 4
The average snowfall of the four days was 6 inches.
What is snow?
When atmospheric water vapor freeze into small ice crystals and falling in small white flakes or lying on the ground as a white layer, it is called snow.
In the question it is said that,
Amount of snow received by the town on first day = 10 inches.
Amount of snow received by the town on second day = 3 inches.
Amount of snow received by the town on third day = 7 inches.
Amount of snow received by the town on fourth day = 4 inches.
Total amount of snow received by the town on these four days = ( 10 + 3+ 7 + 4) inches.
=24 inches.
Hence, average amount of snow received by the town on these four days = total amount of snow received ÷ 4
= ( 24 ÷ 4) inches.
= 6 inches.
Hence, the average snow received by the little town was 6 inches on those days.
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Round the following answer to the correct number of
significant figures. 25.657 + 134.24 = ? *
Answer:
I'm pretty sure its 160, correct me if I am wrong
Explanation:
Answer:
ya it is 160
Explanation:
the original answer is 159.897 so if u round it to 3 Sig u get 160
Give me an example of heterogeneous mixture
Answer:
oil and water
Explanation:
The speed of an object undergoing constant acceleration increases from 8.0 m/s to 12.0 m/s in 10.0 seconds. How far does the object travel during the
10.0 seconds?
4 m
100 m
800 m
10 m
Answer:
is the question finnished
Explanation:
How does an object become negatively charged
Explanation:
When insulating materials rub against each other, they may become electrically charged . Electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. The material that gains electrons becomes negatively charged. The material that loses electrons is left with a positive charge.
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 ".
When a ball is sitting still on top of a table, are the forces acting upon it balanced or unbalanced?
Answer:
Balanced
Explanation:
If a stationary object is staying still (in this case it's the ball) all of the forces acting upon it are balanced. If an object moving has balanced forces, it would move in the same direction at the same speed until a different outside force interrupts the equilibrium.
Hope this helps :)
This question involves the concepts of Newton's Second Law and Balanced Force.
The forces acting upon the ball are "Balanced".
Newton's Second LawAccording to Newton's Second Law whenever an unbalanced force is applied on an object, it produces an acceleration in the object in the direction of the force itself. This acceleration is directly proportional to the magnitude of the force and inversely proportional to the mass of the object.
Since, the ball is at rest and not moving. Hence, it has no acceleration and no unbalanced force is applied on it. The weight of the ball is balanced by the normal reaction provided by the table. Therefore, the forces acting on the ball are Balanced Forces.
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No more energy can be removed from matter at
a. its freezing point.
c. absolute zero
b. 0°С.
d. 273 K.
A delivery drone uniformly slowed down from 45 m/s to 23 m/s in a straight line over a 30-minute duration within a 16-kilometer radius of its warehouse. What was the magnitude of its average acceleration?
A. 1.2 x 10^−2 m/s^2
B. 5.3 x 10^−1 m/s^2
C. 7.3 x 10^−1m/s^2
D. 4.4 x 10^1 m/s^2
define engineering in your own words
Answer:
engeenering
Explanation:
how you design or do something with tools or with hand
Whats the difference between a solar eclipse and a lunar eclipse?
Answer:
A solar eclipse results when the moon passes in between the earth and the sun hiding the sun fully or partly for some time. A lunar eclipse occurs when the earth passes in between the moon and the sun casting its shadow on the moon and thus hiding it fully or partly for some time.
Explanation:
your welcome
A marble accelerates from rest at a constant rate .it travels 36 m in 12.0 sec what’s is it’s final velocity and what was the acceleration
Answer:
a = 0.50 m/s²
v = 6.0 m/s
Explanation:
Step 1: Given data
Initial velocity (u): 0 m/s (rest)Displacement of the marble (s): 36 mTime elapsed (t): 12.0 sFinal velocity (v): ?Acceleration (a): ?Step 2: Calculate the acceleration
We will use the following suvat equation.
s = u × t + 1/2 × a × t²
s = 0 × 12.0 s + 1/2 × a × (12.0 s)²
36 m = a × 72.0 s²
a = 0.50 m/s²
Step 3: Calculate the final velocity
We will use the following suvat equation.
v = u + a × t
v = 0 + 0.50 m/s² × 12.0 s
v = 6.0 m/s