A compound wall consists of parallel layers of two different materials, 10 cm of brick and 2 cm of wood. If the difference of temperature across the brick wall is 20° C calculate the temperature difference between the wooden wall and heat current per square metre of the wall. [Thermal conductivity of brick and wood are respectively 0.5Wm-K- and 0.125Wm-'K']
The temperature difference between the wooden wall is 16⁰C, and the heat current per square metre of the wall is 7,325 W/m².
Temperature difference between the wooden wallThe temperature difference between the wooden wall is calculated as follows;
Let the brick wall = wall ALet the wooden wall = wall BLet the area of the walls = A[tex]\frac{dQ_A}{dt } = \frac{dQ_B}{dt} \\\\\frac{K_A \Delta T_A \times A}{L_A} = \frac{K_B \Delta T _B \times A}{L_B}\\\\\frac{K_A \Delta T_A }{L_A} = \frac{K_B \Delta T _B}{L_B}\\\\\frac{0.5 \times 20}{0.1} = \frac{0.125 \times \Delta T _B }{0.02} \\\\100 = 6.25\Delta T _B\\\\\Delta T _B = \frac{100}{6.25} \\\\\Delta T _B = 16 \ ^oC[/tex]
Heat flowing in the wallsQ = KL(ΔT)
Q = 0.5 x 0.1 x (20 + 273)
Q = 14.65 W
Heat current per square meter of the WallsQA = W/A
QA = (14.65)/A
Let the area of the wall = 10 cm x 2 cm = 0.1 m x 0.02 m = 0.002 m².QA = 14.65/0.002
QA = 7,325 W/m²
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Which red line shows the same action spectrum corrected for the unequal number of photons emitted across the visible spectrum?.
The visible spectrum is composed of red, orange,yellow, green, blue, violet, indigo.
What is visible spectrum?The visible spectrum refers to the portion of the electromagnetic spectrum that can be seen with the eyes. All other portions of the electromagnetic spectrum are invisible.
The question is incomplete as the details are missing. The visible spectrum is composed of red, orange,yellow, green, blue, violet, indigo.
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If you were standing on the edge of a thunderstorm as it begins to form, would the wind be blowing into the storm or out of it? why?
Explain why electromagnetic forces are essential to forming compounds.
Explanation:
formation of compounds because the electric forces compel the atoms to attract each other and formed bonds which leads to the formation of chemical compounds. The attractive or repulsive interaction between any two charged bodies is known as an electric force so the attraction between two opposite charged atoms causes the formation of compounds so we can conclude that electric forces are important for the formation of compounds.
is it possible to make your lifetime displacement zero, if so where would you go?
Answer:
Yes
Explanation:
Displacement is the distance from the starting point to the end point. If you live and die at the same place, you will have 0m as your displacement.
At what distance does the electric field produced by a charge of -15 μc have a magnitude equal to 8. 7×104n/c?
Answer:
we'll use the electric field formula. ı wrote the formula in the photo.
Explanation:
The electric field formula is obtained by multiplying force and charge. When you apply this process I mentioned, you will find an electric field. then it is to write the given values and find the result. achievements.
At the distance for which the electric field produced by a charge of -15 μc have a magnitude equal to 8. 7×104n/c is 3.93 meters.
What is electric force?Electric force is the force of attraction of repulsion between two bodies.
According to the Coulombs law, the force of attraction of repulsion between charged two bodies is directly proportional to the product of charges of them and inversely proportional to the square of distance between them.
It can be given as,
[tex]F=k\dfrac{Q}{r^2}[/tex]
Here, (k) is the coulombs constant, (Q) is the charges and (r) is the distance between the two charges.
The charge of -15 μc have a magnitude equal to 8. 7×104n/c. Put this value in the above formula,
[tex]8.7\times10^4=(8.98\times10^{9})\dfrac{15\times10^{-6}}{r^2}\\r=3.93\rm\; m[/tex]
Thus, at the distance for which the electric field produced by a charge of -15 μc have a magnitude equal to 8. 7×104n/c is 3.93 meters.
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A drum is struck, producing a wave with a wavelength of 110 cm and a speed of
2.42 × 104 m/s. What is the frequency of the wave? What is the period?
Explanation:
wavelength = l
speed of wave = v
frequency = f
v = lf → f = v/l = 2.42 × 10⁴ ÷ 1.1 = 2.2 × 10⁴ 1/s
T = 1/f = 1/ 2.2 × 10⁴ = 0.45 × 10 -⁴ s
The frequency of the sound wave produced from the drum is the speed divided by the wavelength. The frequency of the wave 22 kHz.
What is frequency ?Frequency of a wave is the number of wave cycles per unit time. Frequency of a wave is directly proportional to the energy and inversely proportional to the wavelength.
The relation between speed of the wave c, wavelength and frequency of the wave can be written as follows:
c = νλ.
Given speed of the sound wave produced from the drum = 2.42 × 10⁴ m/s
wavelength λ = 110 cm = 1.1 m
The frequency of the sound wave = speed/wavelength
ν = 2.42 × 10⁴ m/s / 1.1 m = 22000 Hz or 22 kHz.
Time period = 1/frequency
T = 1/ 22000 = 4.45× 10⁻⁵ seconds.
Therefore, the frequency of the wave is 22 kHz and time period of 4.45× 10⁻⁵ seconds.
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Use F = 1/T as your basis:
7. What is the period of 60.0Hz electrical power?
The answer is 16.7 ms but please show your work.
[tex]\\ \rm\rightarrowtail \nu=\dfrac{1}{T}[/tex]
[tex]\\ \rm\rightarrowtail T=\dfrac{1}{\nu}[/tex]
[tex]\\ \rm\rightarrowtail T=\dfrac{1}{60}[/tex]
[tex]\\ \rm\rightarrowtail T=1.67\times 10^{-4}s[/tex]
[tex]\\ \rm\rightarrowtail T=16.7\times 10^{-3}s[/tex]
[tex]\\ \rm\rightarrowtail T=16.7ms[/tex]
Mass m1 on the frictionless table of the figure is connected by a string through a hole in the table to a hanging mass m2
For a mass m1 on the frictionless table, the speed m1 must rotate a with radius r if m2 is to remain hanging at rest is mathematically given as
[tex]v=\sqrt{m1/m2*xg}[/tex]
What speed must m1 rotate in a circle of radius r if m2 is to remain hanging at rest?Generally, the equation for the Force is mathematically given as
Fc=Fw
Therefore
[tex]\frac{m1v1}{x}=m2g[/tex]
[tex]v=\sqrt{m1/m2*xg}[/tex]
In conclusion, if m2 is to remain hanging at rest the speed of ratio of m1 is calcuylated using
[tex]v=\sqrt{m1/m2*xg}[/tex]
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The value of the velocity for the mass m₁ on the frictionless table will be [tex]\rm v = \sqrt{\frac{m_1}{m_2 xg} }[/tex]. Velocity is a time-based component. Its unit is m/sec.
What is velocity?The change of distance with respect to time is defined as speed. Speed is a scalar quantity.
The given data in the problem is
m is the mass
g is the acceleration of free fall =10m/sec²
v is the velocity
From the balancing equation of force the centripetal force is equal to the weight;
[tex]\rm F_c= m_2 g \\\\ \rm \frac{m_1v_1^2}{x} = m_2 g \\\\ v= \sqrt{\frac{m_1}{m_2xg} } \\\\[/tex]
Hence the value of the velocity for the mass m₁ on the frictionless table will be [tex]\rm v = \sqrt{\frac{m_1}{m_2 xg} }[/tex].
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If a food has 200 calories and 7 grams of protein, and each gram of protein is 4 calories, what percent of the serving comes from protein?
Answer: 13%
Explanation: The reason this is 13 is because you can eat carlories and you can also be an amazing person 200 calories and 7 grams
How can we make a simple energy flow diagram to show the heat transfer between animals, heat lamps and environment?
Answer:
Remember a few key things:
1.) Oil comes from plants, but also animals
2.) When heat lamps are done or useless, they go to landfills
3.) Things in landfills go back to the environment after a few years or even decades.
4.) Sometimes there are all-natural oils for heat lamps
1. A temperature unit is known as a
Explanation:
i think is per the International System of Units is Kelvin which is represented by the symbol K.
Two cities in the same climate zone must have the same climate and weather conditions. Why is this statement true or false?
A. It is false because cities in the same climate zone must have different climates.
B. It is false because the two cities might differ in their proximity to water.
C. It is true because the two cities are at the same latitude.
D. It is true because the two cities will be closer to the equator.
Answer:
C
Explanation:
true because c is the best answer
Answer: The answer is C. It is true because the two cities are at the same latitude.
Explanation:
Hi I was doing the same test are u in flvs lol I am too if you are!
state ohm's law and prove V=ir
Answer:
Ohm’s law states that the current flowing through a conductor is directly proportional to the potential difference ( Voltage ) between the terminals of the conductor, provided that, factors such as the temperature of the conductor is kept constant
V = IR, where R is the proportionality constant.
R = resistance (measured in ohms)
V = voltage (measured in volts)
I = current (measured in amps)
hey guys can y’all help quickly?
how to induce a positive temporary charge on the right side of a metal ball
Answer:
Temporary? You have two options
If you have a positively charged object, bring it close to the LEFT side of the ball (not touching it!).
If you have a negatively charged object, bring it close to the RIGHT side of the ball (again, not in contact).
Either way, the electron cloud will migrate towards the right side of the of your sphere.
Another option is to have a capacitor large enough to house the sphere inside it, and polarize it by attaching it to a DC source making sure that the negative plate of it is to the right of the sphere.
Differentiate between transverse wave and longitudinal wave
Explanation:
Transverse wave
The wave in which the particles of the medium vibrate up and down perpendicularly to the direction of the wave is called transverse wave...It consists of crests and troughs...It can be produced only in solids and surface of liquids...Longitudinal wave
The wave in which the particles of the medium vibrate to-and-fro in the direction of the wave is called longitudinal wave..It consists of compressions and refractions...It can be produced in solid , liquid and gas...
[tex] \text \red { \huge\underline{Question}}[/tex]
[tex] \text{What is ideal-gas equation?}[/tex]
Answer:
PV = nRT
Explanation:
The Ideal Gas Equation shows the relation between 4 factors :-
Pressure Volume moles Temperature⇒ R is the molar gas constant included so they are equal to each other, without it, they would just be proportional
The equation :-
⇒ PV = nRT
Which concept is exemplified by being able to distinguish a slight change in light when a dimmer is used to adjust the brightness
Answer:
The just-noticeable concept.
Explanation:
Suppose that two point charges, each with a charge of 1 coulomb are separated by a distance of 1 meter. Determine the magnitude of the electrical force between them
The magnitude of the electrical force between the two identical electrical charges is 8.98755 × 10⁹N.
Given the data in the question;
Single charge each with; [tex]q_1\ and\ q_2[/tex] [tex]= 1C[/tex]Distance between; [tex]r = 1m[/tex]Electric force between; [tex]F = \ ?[/tex]Coulomb's lawCoulomb's law states "that the force between two electrical charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them".
It is expressed as;
[tex]F = k\frac{q_1q_2}{r^2}[/tex]
Here, [tex]q_1\ and\ q_2[/tex] are the two electrical charges, r is the distance between them and k is the Coulomb constant ( [tex]k = 8.98755*10^9 kgm^3/s^2C^2[/tex])
To determine the electrical force between the two charges, we substitute our values into the expression above.
[tex]F = k\frac{q_1q_2}{r^2}\\\\F = (8.98755*10^9 kgm^3/s^2C^2)*\frac{(1C)(1C)}{(1m)^2}\\\\F = (8.98755*10^9 kgm^3/s^2C^2)*\frac{1C^2}{1m^2}\\\\F = 8.98755*10^9 kgm/s^2\\\\F = 8.98755*10^9 N[/tex]
Therefore, the magnitude of the electrical force between the two identical electrical charges is 8.98755 × 10⁹N.
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The magnitude of the electrical force between the two charges is 8.987×10⁹ N.
What is coulomb's law?As per the coulomb's law, the electrical force between any two charges separated by a distance of r is given by the formula,
[tex]F = k\dfrac{q_1q_2}{r^2}[/tex]
Given that the value of q₁ and q₂ is 1 coulomb, while the distance between them is 1 meter. Also, the value of k is 8.987×10⁹ N·m²·C⁻², therefore, the force can be written as,
[tex]F = k\dfrac{q_1q_2}{r^2}\\\\F = (8.987 \times 10^{9}) \times (\dfrac{1 \times 1}{1^2})\\\\F= 8.987 \times 10^{9}\rm\ N[/tex]
Hence, the magnitude of the electrical force between the two charges is 8.987×10⁹ N.
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this one too!! need just 1 answer about this system
Answer:
A
Explanation:
The endocrine system has all of the body's hormones it regulates the biological processes. For example it can help brain development, nervous system development, and it can regulate blood sugar. (This is the closest to A)
25. How long does it take a child on a swing to complete one swing if her center of gravity is 4.00 m below the pivot?
Please include all of your steps with the solution.
[tex]\\ \rm\rightarrowtail T=2\pi\sqrt{\dfrac{l}{g}}[/tex]
[tex]\\ \rm\rightarrowtail T=2\pi\sqrt{\dfrac{4}{9.8}}[/tex]
[tex]\\ \rm\rightarrowtail T=2\pi(0.63887)[/tex]
[tex]\\ \rm\rightarrowtail T=1.27774\pi [/tex]
[tex]\\ \rm\rightarrowtail T=4.012s[/tex]
A car of mass 1200kg moving 90km/hr is brought to rest over a distance of 20m. calculate breaking force.
Answer:
-18,750N
Explanation:
90x1000
-------------
3600
u=25m/s
v=0m/s
v^2=u^2+2as
v=0
=625+(2×a×20)
625+40a
-625=40a
a= -15.625 m/s^2
F=ma
=(1200)(-15.625)
= -18,750N
The presence of which magnetic feature best explains why a magnet can act at a distance on other magnets or on objects containing certain metals? fields dipoles domains forces
The orientation with the largest magnetic torque on the dipole is Orientation B (See attached image).
What is Magnetic Torque?The torque on the dipole is defined as:
τ = µ×B,
where B is the external magnetic field.
The magnitude of this torque is µB sinθ, where θ is the angle between B and µ
Magnetic Torque is highest when;
→ →
µ ⊥ β
That is when θ = 90°. Hence B is the correct answer. Please see attached image.
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Answer:
b
Explanation:
5)A 0.50 kg hockey puck is at rest on ice when you hit it with a hockey stick, applying a force of 100 N for
0.10 seconds. The puck then slides across the ice, where the coefficient of kinetic friction is 0.20. After
sliding for 4 seconds, the puck collides with a 0.80 kg box of donuts. The puck immediately comes to rest
after the collision. How far will the box of donuts slide before coming to rest if the coefficient of friction
between the box and the ice is 0.30.
Answer:
F t = m Δv impulse delivered = change in momentum
Δv = 100 * .1 / .5 = 20 m/s original speed of puck
KE = 1/2 m v^2 = .5 * 20^2 / 2 = 100 J initial KE of puck
E = μ m g d energy lost by puck
Ff = μ m g = m a deceleration of puck due to friction
a = μ g = 9.8 * .2 = 1.96 m/s^2
v2 = a t + v1 = -1.96 * 4 + 20 = 12.2 m/s speed of puck on striking box
m v2 = M V conservation of momentum when puck strikes box
V = m v2 / M = 12.2 * .5 / .8 = 7.63 m/s speed of box after collision
KE = 1/2 M V^2 = .8 * 7.63^2 / 2 = 23.3 J KE of box after collision
KE = μ M g d energy lost by box in sliding distance d
d = 23.3 / (.3 * .8 * 9.8) = 9.91 m distance box slides
Is the following sentence true or false? When two surfaces rub, the irreg-ularities of one surface get caught on those of the other surface.
An object of mass 5kg falls from rest and has a kinetic energy of 1500J midway its journey.
a) what is its potential energy at this point?
b) what is the potential energy it started with?
c) what is it’s kinetic energy before hitting the ground?
Answer:
a) 1500 j
b) 3000 j
c) 34.64 m/s
Explanation:
at halfway point 1/2 of the potential energy has been converted to kinetic energy
so 1 /2 P E = 1500 j
it will still have the OTHER half of its PE 1500 j
c) PE will be entirely converted to KE when it is at the bottom
KE = 1/2 m v^2
3000 = 1/2 (5)(v^2) show v = 34.64 m/s
22. What is the length of a pendulum that has a period of 0.500 s?
Please show all of your steps to find the solution.
6.21 cm
use the pendulum formula : [tex]\sf \bold{\mathrm{T}=2 \pi \sqrt{\frac{\mathrm{L}}{\mathrm{g}}}}[/tex]where
T is time or periodπ is pie = 22/7L is pendulum lengthg is acceleration due to gravityGiven:
T = 0.500 sg = 9.8 m/s²solving step-wise:
[tex]\dashrightarrow \mathrm{T}=2 \pi \sqrt{\dfrac{\mathrm{L}}{\mathrm{g}}}[/tex]
[tex]\sf \dashrightarrow \mathrm{0.5}=2 \pi \sqrt{\dfrac{\mathrm{L}}{\mathrm{9.8}}}[/tex]
[tex]\dashrightarrow \mathrm{\dfrac{0.5}{2 \pi } }=\sqrt{\dfrac{\mathrm{L}}{\mathrm{9.8}}}[/tex]
[tex]\dashrightarrow\sqrt{\dfrac{\mathrm{L}}{\mathrm{9.8}}}= \mathrm{\dfrac{0.5}{2 \pi } }[/tex]
[tex]\sf \dashrightarrow{\dfrac{\mathrm{L}}{\mathrm{9.8}}}= (\mathrm{\dfrac{0.5}{2 \pi } })^2[/tex]
[tex]\sf \dashrightarrow{{\mathrm{L}}= (\mathrm{\dfrac{0.5}{2 \pi } })^2*9.8[/tex]
[tex]\sf \dashrightarrow{{\mathrm{L}}=0.06205922 \ m[/tex]
1 m → 100 cm[tex]\sf \dashrightarrow{{\mathrm{L}}=6.2059\ cm[/tex]
[tex]\sf \dashrightarrow{{\mathrm{L}}=6.21\ cm[/tex] { rounded to nearest hundredth }
Let's see
[tex]\\ \rm\rightarrowtail T=2\pi \sqrt{\dfrac{l}{g}}[/tex]
[tex]\\ \rm\rightarrowtail 0.5=2\pi \sqrt{\dfrac{l}{9.8}}[/tex]
[tex]\\ \rm\rightarrowtail 0.783=\pi \sqrt{l}[/tex]
[tex]\\ \rm\rightarrowtail 0.2494=\sqrt{l}[/tex]
[tex]\\ \rm\rightarrowtail \ell=0.0622m[/tex]
Does a photon emitted by a higher-wattage red light bulb have more energy than a photon emitted by a lower-wattage red bulb
Answer:
The energy of these two photons would be the same as long as their frequencies are the same (same color, assuming that the two bulbs emit at only one wavelength.)
Explanation:
The energy [tex]E[/tex] of a photon is proportional to its frequency [tex]f[/tex]. The constant of proportionality is Planck's Constant, [tex]h[/tex]. This proportionality is known as the Planck-Einstein Relation.
[tex]E = h\, f[/tex].
The color of a beam of visible light depends on the frequency of the light. Assume that the two bulbs in this question each emits light of only one frequency (rather than a mix of light of different frequencies and colors.) Let [tex]f_{1}[/tex] and [tex]f_{2}[/tex] denote the frequency of the light from each bulb.
If the color of the red light from the two bulbs is the same, those two bulbs must emit light at the same frequency: [tex]f_{1} = f_{2}[/tex].
Thus, by the Planck-Einstein Relation, the energy of a photon from each bulb would also be the same:
[tex]h\, f_{1} = h\, f_{2}[/tex].
Note that among these two bulbs, the brighter one appears brighter soley because it emits more photons per unit area in unit time. While the energy of each photon stays the same, the bulb releases more energy by emitting more of these photons.
A student measures the voltage and current between two points in an
electrical circuit. If the voltage is 120 V and the current is 0.5 A, what is the
resistance, according to Ohm's law?
A. 0.00402
Β. 240 Ω
C. 1200
D. 60.00
Answer:
B. 240Ω
Explanation:
The formula between voltage, current and resistance is:
voltage = current × resistance
So resistance = voltage ÷ current
Therefore resistance = 120 ÷ 0.5
Resistance = 240Ω
1. manganese dioxide is used in dey cell . ( Give reason)
2. Fuses are used in a circuit. ( Give reason )
Answer:
1.In dry cells, manganese dioxide acts as a ‘depolariser'.
In the depolarization process, the depolariser is used to remove hydrogen and doesn't allow the voltage to get reduced due to polarisation of the cell . Manganese oxide was used as a depolariser in Leclanché cell .
In zinc-carbon dry cell, the manganese dioxide takes in electrons as it is converted to Manganese III oxide (Mn2O3)
2.The fuse breaks the circuit if a fault in an appliance causes too much current flow. This protects the wiring and the appliance if something goes wrong. The fuse contains a piece of wire that melts easily. If the current going through the fuse is too great, the wire heats up until it melts and breaks the circuit.