Consider two walls, A and B, with the same surface areas and the same temperature drops across their thicknesses. The ratio of their thermal conductivities is kA/kB=4 and the ratio of the wall thickness is LA/LB=2. The ratio of heat transfer rates through the walls qA/qB is:


(a) 0.5

(b) 1

(c) 2

(d) 4

(e) 8

(f) None of them

Answers

Answer 1

Answer:

(c) 2

Explanation:

Heat transfer across the walls due to conduction is given by:

[tex]q = -KA\frac{\Delta T}{L}[/tex]

where,

q = heat transfer rate

K = thermal conductivity

A = Area

ΔT = change in temperature

L = thickness

For wall A:

[tex]q_A = -K_AA\frac{\Delta T}{L_A}[/tex]

For wall B:

[tex]q_B = -K_BA\frac{\Delta T}{L_B}[/tex]

Because the change of temperature and area of walls are the same. Dividing both terms:

[tex]\frac{q_A}{q_B} = \frac{\frac{K_A}{L_A} }{\frac{K_B}{L_B}}\\\\ \frac{q_A}{q_B} =\frac{\frac{K_A}{K_B} }{\frac{L_A}{L_B}}[/tex]

using values given in the question:

[tex]\frac{q_A}{q_B} = \frac{4}{2}\\\\\frac{q_A}{q_B} = 2[/tex]

Therefore, the correct answer is:

(c) 2


Related Questions

What are the most essential skills in Team Handball and why?

Answers

Answer:

The most important skill in handball is passing or throwing

Explanation:

You need to be able to pass the ball with accuracy. Throwing and shooting drills are normally incorporated into every training session for handball.

Answer:

Explanation:

The most important skill in handball is passing or throwing. You need to be able to pass the ball with accuracy. Throwing and shooting drills are normally incorporated into every training session for handball.

verify the law of moment.​

Answers

Explanation:

TO VERIFY THE PRINCIPLE OF MOMENTS WHICH STATES THAT IF A NUMBER OF COPLANAR FORCES ACTIING ON A BODY S ,KEEP IT IN EQUILIBRIUM AND THEIR MOMENT ARE TAKEN ABOUT ANY POINT IN THEIR PLANE,THE SUM OF THE CLOCKWISE MOMENTS ,IS EQUAL TO SUM OF ANTICLOCKWISE MOMENT.

please mark me brainlist :)

Answer:

TO VERIFY THE PRINCIPLE OF MOMENTS WHICH STATES THAT IF A NUMBER OF COPLANAR FORCES ACTING ON A BODY, KEEP IT IN EQUILIBRIUM AND THEIR MOMENT ARE TAKEN ABOUT ANY POINT IN THEIR PLANE, THE SUM OF THE CLOCKWISE MOMENTS,  IS EQUAL TO SUM OF ANTICLOCKWISE MOMENT.

Calculate the distance of the end of a valley bearing in mind that the echo takes 0.7 seconds to be heard from the moment when the sound was produced.a

Answers

Answer:238m

Explanation:Distance = speed x time

Speed = 340 m/s

340 m/s x .07 s = 238m

Write a one paragraph essay about the importance of the different biomolecules in our life.

Answers

Answer:

#tried my bestt

do mark me as brainlist

Biomolecules are made by living organisms and they are made because they are functional. Biomolecules, or at least most of them, do not exist outside of living organisms because they are too complex to be created by chance chemical collisions. The odds of a single average sized protein to form by chance has been calculated at 1 out 10 to the 77th power. Biomolecules REQUIRE intelligent agency to form them.

The four main purposes of biomolecules are:

1. Structure (some proteins)

2. Energy storage and release (carbohydrates)  

3. Protective layers (lipids)

4. Information storage and communication (DNA, RNA, endocrines of numerous various types and manipulated molecules, such as fatty acids)

Why is your weight the same any place on Earth?

Answers

Answer: A person can weigh differently at various place on Earth because of the fluctuations in Earth's gravity, according to a new high-resolution map. ... Earth's gravity is weaker at the equator due to centrifugal forces produced by the planet's rotation

Explanation:

1. An elevator is moving up at a constant velocity of 2.5 m/s, as illustrated in the
diagram below: The passenger has a mass of 85 kg,
a. Construct a force diagram for the passenger

Answers

30kg I know I took the test 30kg

HELP ME PLSSS What are the possible genotypes
of the F, offspring? What are the
possible phenotypes of the F,
offspring?

Answers

Answer:

the answer is b i think

Answer:Within an individual organism, the specific combination of alleles for a gene is known as the genotype of the organism, and (as mentioned above) the physical trait associated with that genotype is called the phenotype of the organism.

Explanation:

The phenotype is the trait those genes express. ... Looking at the possible offspring, each box (or possible offspring) has two copies of the dominant gene. This means there is a 100% chance of the offspring having brown eyes, or being BB. It's important to note here that each box represents a possible offspring.

a hole in a copper plate has a diameter of 1.325 cm at 21C°. At what tempreture is the diameter equal to 1.164 cm

Answers

Answer:14C

Explanation:

In the nucleus ______________
tell cells what to do and how to change.

Answers

Answer:

i believe it is dna

Explanation:

if i remember correctly if the dna tells the cell what to do and how to do it

How far can you get away from your little brother with the squirt gun filled with paint if you can travel at 3 m/s and you have 0.25 min before he sees you?

Answers

Answer:

s = 45 m

Explanation:

The velocity given in the question is uniform. Hence, the formula for the uniform velocity shall be used here. The formula is given as follows:

[tex]s = vt[/tex]

where,

s = distance traveled away from the brother = ?

v = constant speed = 3 m/s

t = time taken = (0.25 min)(60 s/1 min) = 15 s

Therefore, using these values in the formula we get:

[tex]s = (3\ m/s)(15\ s)\\[/tex]

s = 45 m

Radiation present in the environment but not produced by humans is called ______.

Answers

Answer:

background

Explanation:

A 31 kg child is traveling at 4 m/s while sledding down a hill. What is the child's kinetic energy at the bottom of the hill?

Answers

Answer:

K.E = 248 J

Explanation:

Since the child is travelling at a given velocity. The kinetic energy of the child down the hill can be given by the following formula:

[tex]K.E = \frac{1}{2}mv^2\\[/tex]

where,

m = mass of the child = 31 kg

v = velocity of the child = 4 m/s

Therefore,

[tex]K.E = \frac{1}{2}(31\ kg)(4\ m/s)^2\\[/tex]

K.E = 248 J

Give reasons for the following:
a. We should not see the solar eclipse directly through our unaided eyes.
b. Dark patches are seen on the ground when sunlight passes through dense tree.

Answers

Answer:

a)The reason why people are advised not to watch the Solar Eclipse with naked eyes is that when the Moon in direcly between the Earth and the Sun, the rays from the Sun that reach the Earth are more powerful and can permanently damage our retina (most important part of the eye).

Explanation:

b ) The leaves of the trees obstruct (stop) the rays coming from the sun as there is no sun the soil to will be marshy. in some places where the leaves are not thick the sunlight penetrates to the ground... therefore one mostly sees dark patches on the ground in dense forests.

Answer:

The reason why people are advised not to watch the Solar Eclipse with naked eyes is that when the Moon in direcly between the Earth and the Sun, the rays from the Sun that reach the Earth are more powerful and can permanently damage our retina (most important part of the eye).

The leaves of the trees obstruct (stop) the rays coming from the sun as there is no sun the soil to will be marshy. in some places where the leaves are not thick the sunlight penetrates to the ground, therefore one mostly sees dark patches on the ground in dense forests.

3/8 of light initial intensity is absorbed in the breaker with length of 2cm filled with 9% solution. Find the length of the beaker should be used to get transmittance 1/3 for the same solution​

Answers

Answer:

Assume I1 = Io * T1        transmission proportional to thickness

I2 = Io * T2          I is intensity of light absorbed     (3/8 absorbed)

I1 / I2 = T1 / T2

T2 = T1 * (I2 / I1) = 2 * (2/3 / 3/8) = 2 * 16/9 = 32/9   thickness for 2/3 absorbed

The length of the beaker when the transmittance is changed to one-third is 13.78 cm.

The given parameters;

length of the beaker when 3/8 of the light intensity is absorbed = 2 cm = 0.02 m

To find:

the length of the beaker when there is 1/3 transmittance

The length of the beaker is calculated by applying Beer-Lambert law;

[tex]\frac{I}{I_o} = e^{-cl}[/tex]

[tex]\frac{I_1}{I_0} = e^{-cl_1} = \frac{3}{8} \ ----(1)\\\\\frac{I_2}{I_0} = e^{-cl_2}= \frac{1}{3} \ ---- (2)[/tex]

divide equation (1) by equation (2);

[tex]\frac{e^{-cl_1}}{e^{-cl_2}} = \frac{3}{8} \times \frac{3}{1} \\\\ (c \ is \ constant \ for \ both) \\\\e^{-l_1 + l_2} = \frac{9}{8} \\\\l_2 - l_1 = ln(\frac{9}{8} )\\\\l_2 - 0.02 = 0.1178\\\\l_2 = 0.1178 + 0.02\\\\l_2 = 0.1378 \ m\\\\l_2 = 13.78 \ cm[/tex]

Thus, the length of the beaker when the transmittance is changed to one-third is 13.78 cm.

Learn more here: https://brainly.com/question/2506921

The temperature of a black body is 500 and its radiation is of wavelength 600 . If the number of oscillators with energy is 100 , 000, calculate the number of oscillators in the black body with energy 1 . (Accoding to Max. Planck, the number of oscillators with energy ℎ at a particular frequency is given by = = − ( ⁄ ) = − ( ⁄ ) (10 Marks) (b) Calculate the peak wavelength of a black body's radiation if the black body is at a temperature of 20 , 000 . (5 Marks)

Answers

Answer: An equation is missing in your question below is the missing equation

a) ≈ 8396

b) 150 nm/k

Explanation:

A) Determine the number of Oscillators in the black body

number of oscillators = 8395

attached below is the detailed solution

b) determine the peak wavelength of the black body

Black body temperature = 20,000 K

applying Wien's law / formula

λmax = b / T  ------ ( 1 )

T = 20,000 K

b = 3 * 10^6 nm

∴  λmax = 150 nm/k

physical sciences Practical test​

Answers

so ummmm what about ?

because I cant see any actual question?

Which of the following is an electric potential?
O A. 2.50
B. 2.5 N
C. 2.5 V
O D. 2.53

Answers

Answer:

B

Explanation:

just answered that question

Label the parts of the wave.

Answers

Answer:

A: Wavelength  

B: Crest  

C: Trough

D: Amplitude

Answer:

A:

✔ crest

B:

✔ amplitude

C:

✔ trough

D:

✔ wavelength

Explanation:

who plays rob.lox , adopt me here?​

Answers

YESSS!! Itsyagurlsoleill add me :DD
I do :D

Want to be friends?

A DC generator is the same as a(n)
A. electric motor.
B. AC generator.
C. armature.
D. electric current.

Answers

Answer:

A DC generator is the same as a(n)

C. armature

If an object has a mass of 15 kg and has a weight of 30 N, on some remote
planet, what would be the acceleration due to gravity on that planet?

Answers

If a object has a mass of 15kg and has a weight of 30N, on ... 0.96kg

What is the relationship between the density of a substance and the speed of sound through that substance?

Answers

Answer:The greater the density of a medium, the slower the speed of sound. This observation is analogous to the fact that the frequency of a simple harmonic motion is inversely proportional to m, the mass of the oscillating object. The speed of sound in air is low, because air is easily compressible.

Explanation:

PLS HELP, WILL GIVE BRAINLIEST ​

Answers

Answer:

B. x = 50, Y = 100 ,Z= 150

sorry if it's wrong

A rocket experiences a 45,000 N force as it accelerates at 30 m/s/s. What is the mass of the rocket?

Answers

Answer:

15,00kg

Explanation:

here's your solution

=> force = 45,000N

=> acceleration = 30m/s^2

=> mass = ?

=> Mass = force/acceleration

=> mass = 45,000/30

=> mass = 15,00kg

hope it helps

7
Select the correct location on the image.
Objects A and B are brought close to each other. Object A will soon become positively charged. Identify the charge that must transfer for this
situation to occur.
+
A
B

Answers

Answer:

Explanation:

For A to become positively charged, a + charge must transfer from B to A.

The charge that must transfer for object A to become positively charged is the negative charge in object A.

What is charging by conduction?

Charging by conduction occurs when a charged object causes the flow of electron when it comes in contact with an uncharged object.

An object can either be negatively or positively charged. An object is said to be positively charged when it contains more protons than electron.

Therefore, for object A to be positively charged, the charge that must transfer for object A to become positively charged is the negative charge.

Learn more about positive charge here:

https://brainly.com/question/14701820

#SPJ5

what type of wave travels through matter only??

Answers

A mechanical wave can only travel through matter.

Mechanical waves travel through water because waves transfer from one place to another

Se deja caer una piedra en un pozo y al cabo de 10s se oye el choque contra el fondo si la velocidad de sonido es de 330 m/s. ¿ Cuál es la profundidad del pozo?

Answers

Translate : Physically, a stone is dropped into a well and after 10 seconds you can hear the crash against the bottom, if the speed?

Answer : 383 m

the molecules in a solid state have _______ energy then molecules in a gas state​

Answers

Answer:

less

Explanation:

hope this helps....................:)

Caso #1 Leo Messi está jugando la final de la Champion league 2019-2020 y va a cobrar un tiro libre importante, necesita aplicar un análisis para poder alcanzar su objetivo que es acertar el gol. Responder

Answers

Answer:

Tiene que patear el balón cerca del nivel del suelo para conseguir el gol.

Explicación:

Leo Messi necesita patear el balón no en el aire, en el nivel del suelo para poder meter el gol para el equipo. Delante del fútbol hay muchos jugadores del equipo contrario dispuestos a detener el tiro libre de Leo Messi. Cuando Leo Messi patea el balón en el aire, los jugadores también saltan en el aire para detener el tiro libre que atraviesa la cabeza y para conseguir el gol Leo Messi tiene que evitar patear el balón en el aire y patear el balón cerca del nivel del suelo. que puede atravesar a los jugadores oponentes cuando lo saltan para detener el balón a través de sus cabezas para que el balón pase por debajo de sus pies y llegue a la portería.

HELP!!! 50 POINTS


4. Predicting What would have happened, in terms of thermal energy transfer, if the water temperature had originally been10.0°C? Explain your reasoning.

Context:Background InformationThe quantity of energy transferred by heat from a body depends on anumber of physical properties of the body and its surroundings. For a given substance, the rate at which thermal energy is transferred by conduction depends on temperature difference, cross-sectional area,and a thermal conductivity constant that is unique to the substance.By choosing one of these properties as a manipulated variable and making the other properties controlled variables, the effect of the manipulated variable on thermal conduction can be determined experimentally.In this investigation, you will study the rates of cooling of three containers of water of equal volume but different surface area.

Answers

Answer:

do u have a picture of the question?

Explanation:

it would be easier to solve

Other Questions
Which country marched through the French capital and was met with a surrender from Napoleon? Why does the executive office of the president include press and communications staff?The president uses mass media to speak to Congress.The president uses mass media to gain support for policies.The president uses mass media to issue executive orders.The president uses mass media to speak to other countries What is an example of plagiarism?using a friend's essay and calling it one's owncopying a magazine article and posting it on one's blog without asking permissionwriting a story and send it to two publishers at the same timenone of the above Which statement best identifies a problem with this method? Step 1 should not come before Step 4 because different guests will want to celebrate different events. Step 2 should not come before Step 3 because the party's location determines the decorations that should be used. Step 3 should not come before Step 4 because the amount of food needed depends on the number of guests invited. Step 4 should not come before Step 5 because the party games or activities are more important than which guests are invited. Summarize how the bargaining stage is related to loss.answer: get back what once was lost to timeget back what once was minewhat once was mine What does it mean to be Un-American? What do you think it meant to be Un-American in the 1940s and 1950s? 1.35 m solution NaOCl in water is prepared. What is the mole fraction of the NaOCl? In which relationship do both species benefit?MutualismCommensalismParasitism Stella wants to buy a $177,000 house, and she is comparing a 7/1 ARM with an interestrate of 8 75%, amortized over 30 years, with a 7/23 balloon mortgage that has aninterest rate of 8.25%24. What would Stella's monthly payment be for the 7/1 ARM? The circle graph shows carla's spending. If she spent a total of $320, how much was spent on food? if a woman is found to have damage to both of her ovaries, can the woman still get pregnant? Please solve these systems of equations by substitution.1. x+y=7x+2y=112. x+y=22x+2y=483. x+y=45x+2y=36 I need to solve for x. The interior angles are 30 and 4x+2. The exterior angle is 8+6x. Enlightenment ideas about ___________________ _________________ of ______________, _______________________ and ________________________ were becoming well-known around the time of the American Revolution. help me please i love you can sombody solve this which of the following is equivalent to the expression below when x >0? 9.A standard IQ test produces normally distributed results with a mean of 100 and a standard deviation of 15. A class of high school science students is grouped homogeneously by excluding students with IQ scores in either the top 15% or the bottom 15%. Find the lowest and highest possible IQ scores of students remaining in the class.(7) find the value of x. Pregunta matemtica When are atoms considered stable?when they have satisfied the law of conservation of mass naturally or through bonding to obtainfull valence shellswhen they have satisfied the octet rule naturally or through bonding to obtain full valence shellswhen their valence electrons have "fallen" back to ground state through bonding