(a) Calculate the rate of heat conduction through house walls that are 13.0 cm thick and that have an average thermal conductivity twice that of glass wool. Assume there are no windows or doors. The surface area of the walls is 120 m2 and their inside surface is at 18.0 oC, while their outside surface is at 5.0 oC. (b) How many 1-kW room heaters would be needed to balance the heat transfer due to conduction

Answers

Answer 1

Answer:

a. 960 W b. One 1 kW room heater

Explanation:

a. The rate of heat conduction P = kA(T₂ - T₁)/d where k = 2 × 0.040 W/m-K =  0.080 W/m-K since the thermal conductivity of glass wool is 0.040 W/m-K and that of the material is twice the thermal conductivity of glass wool, A = area of walls = 120 m², T₁ = outside surface temperature = 5.0 °C, T₂ = inside surface temperature = 18.0 °C and d = thickness of wall = 13.0 cm = 0.13 m

P = kA(T₂ - T₁)/d

= 0.080 W/m-K × 120 m²(18.0 °C - 5.0 °C)/0.13 m

= 9.6 Wm/K × 13 K/0.13 m

= 124.8 Wm/0.13 m

= 960 W

b. The number of 1 kW room heater required will be

n = rate of heat conduction/power of one room heater = 960 W/ 1 kW = 960 W/1000 W = 0.96 ≅ 1

So we need only one 1 kW room heater.


Related Questions

describe three way of nitrogen fixation in nature ?

Answers

Explanation:

nitrogen fixation is the process by which nitrogen gas form the atmosphere is converted into different compound that can be used by plants and animal. there are three major ways in which this happens: first, by lightning, second by industrial methods and finally by bacteria living in the soil.

i) A 100 W and 60 W bulb are joined in series and connected to the mains. Which bulb
will glow brighter? Why?
ii) A 100 W and a 60 W bulb are joined in parallel to the mains. Which bulb will
glow brighter? Why?​

Answers

Answer:

i) 60 W

ii) 100 W

Explanation:

In each case, the bulb that dissipates the most power is the bulb that glows brighter.  Power is voltage times current (P = VI).  Using Ohm's law, we can rewrite this as P = I²R or P = V²/R.

Bulbs are rated at a certain power for a certain voltage.  P = V²/R, so the bulb with the lower resistance will have the higher power rating.  Therefore, the 100 W bulb has a lower resistance than the 60 W bulb.

i) They are in series, so they have the same current.  P = I²R, so the bulb with the higher resistance will glow brighter.  That's the 60 W bulb.

ii) They are in parallel, so they have the same voltage.  P = V²/R, so the bulb with the lower resistance will glow brighter.  That's the 100 W bulb.

A square is cut out of a copper sheet. Two straight scratches on the surface of the square intersect forming an angle theta. The square is heated uniformly. As a result, the angle between the scratches?a) increasesb) decreasesc) stays the samed) depends on whether theta is obtuse or acute

Answers

Answer:

a) increases

Explanation:

Almost all substance or material undergoes expansion due to heating. Heat gives thermal energy to the molecules of a substance increasing their body temperature. The temperature of a substance is the measure of the average kinetic energy of the molecules of that substance. When the temperature of a substance increases, the molecules begin to agitate and try to move far from each other, leading to either a linear, area, or cubic expansion, or all three of them. Metals like copper expand very well on heating, and their expansion is relatively minute, but very observable. When the face of such a copper is scratched to give and angle, heating the copper uniformly will cause the copper to expand, leading to an increase in the angle formed.

explore how archemides principle is applied in building a ship and submarine​

Answers

Answer:

Principle Archimedes is applied in building a ship and submarine using the manipulating that buoyancy, is controlled the ballast tank system.

Explanation:

Submarine is rather had they focused on main parts of the submarine,he is complex and long process implementation,the most submarine design like submarine stability.

Submarine stability is complete and the fundamental Archimedes principle to arrive the weight of submarine is equal to buoyancy force.

Submarine into the parts and components of ballast tank the sequence in diving and surfacing,there two vital parts:-  flood parts and air vents

flood parts:- at the bottom position and allow water to enter or leave that tank.

air vents:- air vents at the top of the pressure hall,and that they submarine dive.

this time submarine is most modern system is depth is 300 to 450 meters,high pressure  air is 15 bar is tank air valve.

submarine is basic of the effective volume of all the submarine surfaced condition,submarine minus to the free water flood is equal to the fully pressure hull,submarine is the surfaced condition.

state three effects of malnutrition in farm animals​

Answers

Answer:

Cows,Pigs,Chicken. They are always in farm

A physical inventory on December 31 shows 3500 units on hand. Bonita sells the units for $15 each. The company has an effective tax rate of 20%. Bonita uses the periodic inventory method. The weighted-average cost per unit is

Answers

The answer would be 10,500 be cause you multiply 3500 times 15 and you get 52500 the you multiply that by .20 and you get 10,500.

Which example best describes a restoring force?
any force that is applied to a spring to change its length
the force applied to stretch a spring and increase its length
the force applied to restore a spring to its original length
the force applied to compress a spring and shorten its length

Answers

Answer:

the force applied to restore a spring to its original length

Explanation:

calculate the power of an engine which can supply 60kg of energy per minute​

Answers

Answer:

1 Watt

Explanation:

Power (P) = w / Δt

w = work done

Δt = change in time

Power (P) = 60kg / 60 seconds

Power (P) = 1 Watt

Un pez llamado PARGO ROJO vive a grandes profundidades. Si se pesca, al salir a la superficie puede tomar el aspecto de la foto porque su vejiga natatoria aumenta de volumen al disminuir la presión. La ley que lo explica es...

Answers

Answer:

Hay diversas leyes que podemos usar acá.

Acá sabemos que la vejiga aumenta su tamaño al reducir la presión, esto tiene sentido, pues al haber menos presión, hay menos fuerza que comprime la vejiga, lo que le permite aumentar su volumen.

Acá tenemos una relación inversa de la forma: V = K/P

Una relación inversa donde la presión esta en el denominador y K es un termino que no depende ni del volumen ni de la presión.

Entonces, a medida que aumenta P, el denominador aumenta, por lo que el valor del volumen decrece.

Un ejemplo de una ecuación similar es la del gas ideal, por ejemplo, para un gas ideal dentro de un globo de volumen V para una dada presión P:

V = nRT/P

donde n es el numero de moles, R es la constante termodinámica y T es la temperatura, acá podemos ver que esta ecuación tiene la misma forma fundamental que la escrita arriba.

a metre rod on wedge is example of unstable equilibrium.why

Answers

Answer:

because it has no balance

Question is on the picture. Answers: A. 0.1 J/g*C B. 0.2 J/g*C C. 0.4 J/g*C D. 4 J/g*C

Answers

Answer:

B. 0.2 J/g/°C

Explanation:

The solid phase is the first segment (from 0°C to 50°C).

q = mCΔT

200 J = (20 g) C (50°C)

C = 0.2 J/g/°C

1. Determina el momento que produce una fuerza de 7 N tangente a una rueda de un metro de diámetro, sabiendo que el punto de aplicación es el mismo borde de dicha rueda provocando un impulso en el sentido de las agujas del reloj. Solución:

Answers

Answer:

τ= F r     into the blade

Explanation:

The moment of a force is defined by

         τ = F x r

where the bold indicates vectors

Let us write in the expression in magnitude

         τ = F r sin θ

in our case the force is tangent to the wheel therefore the angle between F and the radius is 90º, and the sin 90 = 1

       τ= F r

The direction of τ can be used by the rule of the right hand, the fingers curve in the direction of the torque when advancing from the force to the radius and the thumb points in the direction of the torque.

In this case, for a clockwise rotation, the fingers are curved in the direction and the thumb points into the blade, this is the direction of the τ.

TRASLATE

El momento de una fura es definido por

         τ = F x r

donde la negrillas indican vectores

Escribamos en ta expresión en magnitud

          τ = F r sin θ

en nuestro caso la fuerza es tangente a la rueda por lo tanto el angulo entre F y el radios es 90º, y el sin 90=1

        τ = F r

la dirección de tau la podemos  usar la regla de la mano derecha, los dedos curva en la dirección del torque al avanzar dese la fuerza al radio y el pulgar apunta en la dirección del torque.

En este caso para un giro en sentido horario los dedos se curvan ente sentido y el pulgar apunta hacia dentro de lla hoja, esta es la dirección del troque

An object is moving along a circular track of radius 7 m with constant speed 11 m/s. Its average velocity after 8 second of the start is

Answers

Answer:

0 m/s

Explanation:

Average velocity is displacement over time.

v_avg = Δx / Δt

Displacement is the distance between the start and the finish.

The circumference of the track is:

C = 2πr

C = 2π (7 m)

C ≈ 44 m

The distance covered by the object is:

d = vt

d = (11 m/s) (8 s)

d = 88 m

So the object travels 2 circumferences, meaning it ends back where it started.  Therefore, the displacement is 0 m, and the average velocity is 0 m/s.

A magnet pulls a piece of iron with a force of 1 N. What is the force that the iron piece exerts on the magnet?
The iron piece exerts a force of 1 N divided by the ratio of the weight of the iron piece to the weight of the magnet in the same direction.
The iron piece exerts a force of 1 N on the magnet in the opposite direction.
The iron piece exerts a force of 1 N divided by the ratio of the weight of the iron piece to the weight of the magnet in the opposite direction.
The iron piece exerts a force of 1 N on the magnet in the same direction.

Answers

Answer:

the final statements the correct one is. The second

The iron piece exerts a force of 1 N on the magnet in the opposite direction

Explanation:

In this exercise they give us the force exerted by a magnet on an iron bar and ask us the force that the iron bar exerts on the magnet. We can see that these are action and reaction forces, which by Newton's third law must be of equal magnitude and opposite direction, each applied to one of the bodies.

the final statements the correct one is. The second

The iron piece exerts a force of 1 N on the magnet in the opposite direction

What evidence supported the inflation theory? (the big bang theory one pls)

Answers

Answer:

The comic microwave background

Explanation:

The cosmic microwave background is said to be part of the remnant of the Big Bang that happened which resulted in the formation of the universe. This is because the universe was thought to be a very hot place which resulted in the expansion of it.

The heat was said to have resulted in the cooling of gases present and the remnant of the heat is what formed the radiation called the cosmic wave background.

Which term describes the ability to process many things simultaneously?

O Effortful processing

O Parallel processing

O Mood congruent memory

O Flashbulb memory

O Working memory

Answers

Answer:

Parallel processing

Explanation:

It is a parallel processing because it involves the brain processing many part of problem simultaneously.

The brain natural mode of information involves performing many task .

It is also ability of the brain to simultaneously process incoming stimuli or signals of different quality. It is a part of brain's vision and divide what is seen into four major parts which are color, motion, shape, and depth.

Answer: B)  Parallel processing

A man of mass 75kg stands on a weighing machine in a lift. Determine the reading of the weighing machine when the lift is moving: 1. Upwards with an acceleration of 2m/s² 2. Downwards with a constant velocity of 1.5m/s 3. Downwards with an acceleration of 2.5m/s²

Answers

Explanation:

Given that,

Mass of a man, m = 75 kg

(1) We need to find the reading of the weighing machine when the lift is moving upwards with an acceleration of 2 m/s². When the lift is moving upward, reading of the weighing machine is given by :

R = m(g+a)

R = 75 (9.8+2)

R = 885 N

(2) When the lift is moving downwards with a constant velocity of 1.5m/s. It means that the lift is at rest. So, the reading is :

R = mg

R = 75 (9.8)

R = 735 N

(3) When the lift is moving downwards with an acceleration of 2.5 m/s². In this case,

R = m(g-a)

R = 75 (9.8-2.5)

R = 547.5 N

Hence, this is the required solution.

Please give best dialogue in photo that is attached And you are marked as Brainliest

Answers

Answer:

The correct answer is

Explanation:

Character 1: Why are these comic books so hard to read? Can u read them?

Character 2: No it's easy to read Tigger. It's because you are an animal an I am a human being. U don't know how to read.

Hope this helps....

Have a nice day!!!!

Answer:

Dialogue 1:

Hey buddy! Can you tell me what is written in this book? Its really hard to read:(

Dialogue 2:

Yeah! Its a story about a friendly tiger! And it is hard for you to read cause you don't know how to read.

Tip:

Try to make it more engaging  :)

A cell membrane has a thickness of about 7 nm. How many cell membranes would it take to make a stack 2.3 in high?

Answers

Answer:

There are 8345714 cell membranes.

Explanation:

It is given that,

The thickness of a cell membrane is 7 nm

We need to find the number of cell membranes would it take to make a stack 2.3 inches high.

Firstly, the units must be same i.e. converting 2.3 inches to m

1 inch = 0.0254 m

2.3 inches = 0.05842 m

Let there are n number of cell membranes. So,

[tex]n=\dfrac{\text{stack height}}{\text{1 membrane thickness}}\\\\n=\dfrac{0.05842}{7\times 10^{-9}}\\\\n=8345714.28[/tex]

or

n = 8345714 cell membranes

how do you find average velocity

Answers

Answer:

find the sum of the inital and final velocitys and divide by 2 to find the average

Earth orbits 1 AU from the Sun, and the Oort cloud extends from about 10,000 to 100,000 AU from the Sun. If you represent Earth’s orbit around the Sun with a paper plate 4 inches in radius, how far away will the inner edge of the Oort Cloud be? The outer edge? Express your answers in miles.

Answers

Explanation:

Earth’s orbit around the Sun represented as :

1 AU = 4 inches

Therefore,

Inner edge of the Oort Cloud represented as :

10,000 AU = 40,000 / 63360 = 0.631 miles

Outer edge of the Oort Cloud represented as:

100,000 AU = 400,000 / 63360 = 6.31 miles

Please Help
A skydiver jumps out of a hovering helicopter, so there is no forward velocity. Use this information to answer questions. Ignore wind resistance for this exercise.
3. What is the skydiver's velocity after one second? Show your work and include direction.

Answers

Answer:

The velocity and direction after 1 second is 8.1 m/s downwards

Explanation:

The equation of motion for an object in free fall can be written as follows;

v = u + g×t

Where;

v = The final velocity of the object

u = The initial velocity of the object = 0 m/s

g = The acceleration due to gravity = 9.81 m/s²

The velocity after one second is given by the velocity equation as follows;

v = 0 + 9.81 m/s² * 1 s = 9.81 m/s

The direction of the is downwards due to the attraction by the Earth's gravitational field which acts towards the Earth's center

Therefore, the velocity and direction after 1 second is 8.1 m/s downwards.


A wave has a frequency of 5 Hz and a wavelength of 0.5 m, what is the speed of this wave?

Answers

Answer:

2.5 m/s

Explanation:

The speed of a wave can be found using the following formula.

v= λ * f

where  λ is the wavelength in meters (m) and f is the frequency of the wave in Hertz (Hz).

We know the wavelength is 0.5 m and the frequency of the wave is 5 Hz.

Therefore,

λ= 0.5 m

f = 5 Hz

v= 0.5 * 5

Multiply 0.5 by 5, or divide 5 by 2.

0.5 * 5= 2.5     or      5/2=2.5

v= 2.5

Add appropriate units. The units for wave speed are m/s (meters per second).

v= 2.5 m/s

The speed of the wave is 2.5 meters per second.

we hammer the broader side of a nail and not its sharp end to put it in wood .why ?

Answers

Explanation:

We hammer the broader side of a nail instead of its sharp end to put it in wood. It is a concept based on the pressure exerted.

The force acting per unit area of an object is called pressure exerted. It means that pressure is inversely proportional to the area of cross section i.e. area increases, pressure decreases and vice versa.

The broader side of a nail has more area as compared to the sharp end. It means that the broader side will exert less pressure on them which make it easier for us to fix it into the wood.

Jaiden is writing a report about the structure of the atom in her report,she says that the atom has three main parts and two subatomic particles. Do you agree with her?why or why not

Answers

Answer:

I do not agree with the answer.

Because in reality, the atom has 2 main parts and 3 subatomic particles.

Explanation:

The parts of an atom are:

- The crust: It is the outer part of the atom and is the place where the electrons are.

- The nucleus: It is the central part of the atom and is the place that contains the protons and neutrons.

The subatomic particles of the atom are:

- Electrons: They are negatively charged particles that go in the atom's crust and are divided into specific sections.

- Protons: They are particles with a positive electric charge, the number of protons in the nucleus of an atom is what determines the atomic number of an element.

- Neutrons: They are atoms with no electric charge.

A ball is thrown vertically upwards at an initial speed of
23
m s

1
. What is the displacement of the ball 3 seconds after it was thrown?

Answers

Answer:

114m

Explanation:

s=ut + 1/2 at^2

s=23 m/s ×3s + 1/2×3×3s^2×10m/s^2

= (69+45)m

= 114m

The motion of a particle along a straight line is described by the equation x=6+4t2 -t 4 , where x is in meter and t is in seconds. Find position, velocity, and acceleration of the object when t=2s.

Answers

Answer:

The position of the particle is 6m

The velocity of the particle is 16 m/s in negative direction

The acceleration of the object is -40 m/s²

Explanation:

Given;

motion of the particle along a straight line as x = 6 + 4t² - t⁴

The position of the object when t = 2s

x = 6 + 4(2)² - (2)⁴

x = 6 + 16 - 16

x = 6m

The velocity of the object when t = 2s

Velocity = dx/dt

dx/dt = 8t - 4t³

when t = 2s

Velocity = 8(2) - 4(2)³

Velocity = 16 - 32

Velocity = -16m/s

Velocity = 16 m/s (in negative direction)

The acceleration of the object when t = 2s

Acceleration = d²x/dt² = 8 - 12t²

Acceleration = 8 - 12 (2)²

Acceleration =  -40 m/s²

what is the scientific notation for 1,500,000​

Answers

Answer:

[tex]1.5 * 10^6[/tex]

Explanation:

Given

Digit: 1,500,000

Required

Represent using scientific notation

We start by expressing the given digit as a product of 1.5 and a multiple of 10

[tex]Digit = 1.5 * 1,000,000[/tex]

1,000,000 can be represented as 10⁶

So; the digit becomes

[tex]Digit = 1.5 * 10^6[/tex]

Hence, the scientific notation of 1,500,000 is 1.5 * 10⁶

the unit of energy is a derived unit​

Answers

Explanation:

Hi, there!!

Energy is defined as the capacity or ability to do work. It's SI unit is Joule.

here,

Joule = (kg×m×m)/(s×s)

= kg×m^2/s^2.

Therefore, the derived unit is kg.m^2 by s^2.

Hope it helps...

Astronomers were at first surprised to find complicated molecules in the interstellar medium. They thought ultra-violet light from stars would break apart such molecules. What protects the molecules we observe from being broken apart

Answers

Answer:

The dust present in the clouds.

Explanation:

The complicated composition molecules that can be found in space are generally associated with clouds of dust. The significant amount of dust in these clouds provides protection not only for these molecules, but for any body that makes up or is associated with dust clouds.

It is exactly this dust that protects the molecules against the action of ultraviolet rays.

Other Questions
The immune response of a host against an invading bacterium is often triggered by surface components on the bacterium that are recognized as "non-self" or "foreign" by the host. These non-self components, often protein or polysaccharide in nature, are referred to as antigens. The host responds to these antigens by making antibodies that will react with invading bacteria and mark them or tag them for destruction by phagocytes. Indicate the bacterial structures that are likely to be antigens, to which host antibodies bind, marking the invader for phagocytosisa. fimbriaeb. ribosomesc. cell walld. plasmidse. flagellaf. capsuleg. nucleoid If you perceive that the costs and rewards are balanced between you and your partner, you are more likely to be satisfied with your relationship. a. True b. False There are 2229 students in a school district. Among a sample of 452 students from this school district, 163 have mathematics scores below grade level. Based on this sample, estimate the number of students in this school district with mathematics scores below grade level. a. 804 b. 844 c. 884 d. 0.36 convert 28km into cm is an example of a country that combines communism with a free market. If sail boats A and B are approaching each other with the wind on different sides, why is vessel A considered the give-way vessel (vessel that must take early and substantial action to avoid a collision)? PLEASE FOR THE LOVE OF FOOD ANSWER MY QUESTION!Given that a quadrilateral PQRS is a parallelogram, PQ and RS are opposite sides, PQ = 7x + 16, RS = 5x +28, and QR = 67 which of the following statements are correct? More than one answer may be correct. Programs that increase social interpersonal competence and decrease __________ tend to reduce delinquency. Group of answer choices Vaughn Manufacturing is constructing a building. Construction began in 2020 and the building was completed 12/31/20. Vaughn made payments to the construction company of $3114000 on 7/1, $6456000 on 9/1, and $5950000 on 12/31. Weighted-average accumulated expenditures were Which of the following statements is false? a. A feasible solution satisfies all constraints. b. In a linear programming problem, the objective function and the constraints must be linear functions of the decision variables. c. It is possible to have exactly two optimal solutions to a linear programming problem. d. An optimal solution to a linear programming problem can be found at an extreme point of the feasible region for the problem. 03. O preo a ser pago por uma corrida de txi inclui uma parcela fixa, denominada bandeirada, e uma parcela que depende da distncia percorrida. Se a bandeirada custa R$ 3,20 e cada quilmetro rodado custa R$ 1,50, qual o valor de v a pagar em uma corrida de n quilmetro? * 1 ponto a) v = 1,50 + 3,20n b) v = 3,20.N c) v = 3,20.N - 1,50 d) v = 3,20 + 1,50n e) v = 1,50n An octagonal pyramid ... how many faces does it have, how many vertices and how many edges? A triangular prism ... how many faces does it have, how many vertices and how many edges? a triangular pyramid ... how many faces does it have, how many vertices and how many edges? The Case of Susan B. Anthony: Which of these inferences about the Anthony case is best supported by the text? Question 11 options: a) Anthony was majorly discouraged when the trial was moved to another county. b) Anthony is solely focused on her own self-interest. c) Local and state authorities are eager to bring their own charges against Anthony as well. d) The district attorney and federal authorities seem extremely motivated to prosecute Anthony. Which term describes the ability to process many things simultaneously?O Effortful processingO Parallel processingO Mood congruent memoryO Flashbulb memoryO Working memory how do you find average velocity If Robert thinks that the only way in this world for a person to know whether God exists is to have some kind of sensory experience of God, along with an active mind that is able to process, structure and arrange ones experiences in a way that makes sense to him, then Robert would be following Kant in thinking that:__________ An electron moving in the direction of the +x-axis enters a magnetic field. If the electron experiences a magnetic deflection in the -y direction, the direction of the magnetic field in this region points in the direction of the:______ From which area of study does the four Quadrant Model originate there are 5 discs, 6 jump ropes, 3 balls, and 12 pieces of sidewalk chalk in a bin. If two items are drawn at random without replacement, what is the probability that both items removed are not jump ropes? What is the volume of a cube with side lengths that measure 8 cm?