Explanation:
The kinetic energy of an object is given by :
[tex]E=\dfrac{1}{2}mv^2[/tex]
m is mass of the object
v is the speed of the object
It is clear from the above relation that the kinetic energy of the object is directly proportional to the product of mass and velocity.
The hypothesis can be :
If the speed of the object increased then its kinetic energy increase because kinetic energy is directly proportional to ist speed.
The kinetic energy of an object is given by :
m is mass of the object
v is the speed of the object
It is clear from the above relation that the kinetic energy of the object is directly proportional to the product of mass and velocity.
The hypothesis can be :
If the speed of the object increased then its kinetic energy increase because kinetic energy is directly proportional to its speed.
Average velocity is different than average speed because calculating average velocity involves a)Distance b)Time c)Motion d)Displacemnet
Answer:
D. Displacement
Explanation:
got it right on edge
Average velocity is different than average speed because calculating average velocity involves Displacement, therefore the correct option is option D.
What is Velocity?The total displacement covered by any object per unit of time is known as velocity. It depends on the magnitude as well as the direction of the moving object. It can also be represented by the infinitesimal rate of change of displacement with respect to time. The unit of velocity is meter/second.
The mathematical expression for velocity is given by
velocity= displacement / time taken
In the displacement time graph the slope of the curve represent the velocity of the object ,the rate of change of velocity is known as the acceleration of the object .
In the velocity time graph the slope of the curve represent the acceleration of the body, The unit of acceleration is metre per second Square
The total distance traveled by an object is different than the total displacement covered by it because the displacement is a vector quantity and it is calculated on the basis of the shortest distance traveled by the body or object.
The main difference between the distance and the displacement is that displacement can be positive or negative or zero but distance can never be negative.
Let’s understand understand with example of average velocity ,suppose an object is moving with 200 m displacement covered in a time of 15 seconds then the average velocity of the object is 13.33 m/s.
Thus, average velocity is different than average speed because calculating average velocity involves Displacement, therefore the correct option is option D.
Learn more about Velocity from here
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Show that energy dissipated due to motion of a conductor in the magnetic field is due to mechanical energy.
Explanation:
let us use the explanation below to get the intuition so desired;
According to Faraday's law of electro magnetic induction, when ever a coil/conductor is made to rotate in a magnetic field, voltage or emf is created and current is produced, in the long run energy has be produced or converted.
The conversion of this energy is made possible by the motion of the coil/conductor is the magnetic field, just by the motion of the conductor cutting through the magnetic field, thus creating electro motive force(E.M.F) hence producing current, and ultimately energy is created
(a) In electron-volts, how much work does an ideal battery with a 17.0 V emf do on an electron that passes through the battery from the positive to the negative terminal? (b) If 3.88 × 1018 electrons pass through each second, what is the power of the battery?
Answer:
(a) 17.0eV
(b) 10.55W
Explanation:
(a) The amount of work done (W) on an electron by an ideal battery of emf value of V as it moves from the positive to the negative terminal is given by;
W = q x V --------(i)
Where;
q = charge on the electron = 1e
From the question;
V = 17.0 V
Substitute the values of q and V into equation (i) as follows;
W = 1e x 17.0
W = 17.0eV
Therefore, the work done in electron volts is 17.0
(b) The power (P) of the battery as some electrons (n) pass through it at time t, is given as;
P = (n q V) / t --------------(ii)
Where;
n = number of electrons = 3.88 x 10¹⁸
t = 1s
q = 1.6 x 10⁻¹⁹C
V = 17.0V
Substitute these values into equation (ii) as follows;
P = (3.88 x 10¹⁸ x 1.6 x 10⁻¹⁹ x 17.0) / 1
P = 10.55W
Therefore the power of the battery is 10.55W
Select the correct answer.
According to the Universal Law of Gravitation, every object attracts every other object in the universe. Why can’t you feel the force of attraction between you and Mars?
A.
There is no force of attraction between you and Mars.
B.
Your mass is too low.
C.
Mars is a larger planet than Earth.
D.
Mars is a long distance away.
Answer:
D. Mars is a long distance away
A massless, rigid board is placed across two bathroom scales that are separated by a distance of 1.89 m. A person lies on the board. The scale under his head reads 470 N, and the scale under his feet reads 334 N. (a) Find the weight of the person. (b) Locate the center of gravity of the person relative to the scale beneath his head.
Answer:
A. 119kg
B.0.53m from head
Explanation:
A. Weight = 730+340.
=1170N
F= Wg
W = 1170/9.8
= 119kg
If x is distance from head to CG then 1.92–x is the other distance.
Moments must equal
470x = 330(1.89–x)
470x = 623.7 – 330x
1170x = 623.7
x = 0.53m from head
A 24 cm radius aluminum ball is immersed in water. Calculate the thrust you suffer and the force. Knowing that the density of aluminum is 2698.4 kg / m3
Answer:
W =1562.53 N
Explanation:
It is given that,
Radius of the aluminium ball, r = 24 cm = 0.24 m
The density of Aluminium, [tex]d=2698.4\ kg/m^3[/tex]
We need to find the thrust and the force. The mass of the liquid displaced is given by :
[tex]m=dV[/tex]
V is volume
Weight of the displaced liquid
W = mg
[tex]W=dVg[/tex]
So,
[tex]W=dg\times \dfrac{4}{3}\pi r^3\\\\W=2698.4\times 10\times \dfrac{4}{3}\times \pi \times (0.24)^3\\\\W=1562.53\ N[/tex]
So, the thrust and the force is 1562.53 N.
Find the mass. 10 points. Will give brainliest.
Answer:
3.94 kgExplanation:
Given,
Force ( f ) = 30 N
Acceleration(a) = 7.6 m/s
Now, Let's find the mass of the ball
Using the Newton's second law of motion:
We get:
[tex]force \: = mass \: \times acceleration[/tex]
plug the value
[tex]30 \: = m \: \times 7.6[/tex]
Use the commutative property to reorder the terms
[tex] 30 = 7.6 \: m[/tex]
Swap the sides of the equation
[tex]7.6m = 30[/tex]
Divide both sides of the equation by 7.6
[tex] \frac{7.6 \: m}{7.6} = \frac{30}{7.6} [/tex]
Calculate
[tex]m = 3.94 \: kg[/tex]
Hope this helps..
Best regards!!
Answer:
[tex]\displaystyle \boxed{\mathrm{3.95 \: kg }}[/tex]
Explanation:
[tex]\mathrm{force \: (N) = mass \: (kg) \times acceleration \: (m/s^2)}[/tex]
[tex]\mathrm{force = 30N}[/tex]
[tex]\mathrm{acceleration = 7.6 \: m/s^2 }[/tex]
[tex]\mathrm{Find \: the \: mass.}[/tex]
[tex]\mathrm{30 = m \times 7.6}[/tex]
[tex]\displaystyle \mathrm{m =\frac{30}{7.6} }[/tex]
[tex]\displaystyle \mathrm{m = 3.947... }[/tex]
Allocate birr 5000 among the three workers in the ratio 1/3 :1/6 and 5/12.
Answer:
1666.7 ETB (birr)
833.3 ETB (birr)
2083.3 ETB (birr)
Explanation:
The first worker
5000*1/3=1666.7
The second worker
5000*1/6=833.3
The third worker
5000*5/12=2083.3
Hope this helps :) ❤❤❤
A plane drops a package for delivery. The plane is flying horizontally at a speed of 120m/s,and the package travels 255 m horizontally during the drop. We can ignore air resistance.What is the package's vertical displacement during the drop?
Answer:
Package's vertical displacement(s) = 22.12 meter
Explanation:
Given:
Speed of plane = 120 m/s
Total distance = 255 m
Find:
Package's vertical displacement(s)
Computation:
Time taken = Distance / Speed
Time taken = Total distance / Speed of plane
Time taken = 255 / 120
Time taken = 2.125 s
Acceleration due to gravity(g) = 9.8 m/s²
Initial velocity (u) = 0
So,
Package's vertical displacement(s) = ut + (1/2)gt²
Package's vertical displacement(s) = (0)(2.125) + (1/2)(9.8)(2.125)²
Package's vertical displacement(s) = 22.12 meter
Answer: -22.1
Explanation:
I just did the Khan Academy and that was the answer, not the one provided by that one person. :)))
1. Analogies exist between rotational and translational physical quantities. Identify the rotational term analogous to each of the following: acceleration, force, mass, work, translational kinetic energy, linear momentum, impulse.
2. Explain why centripetal acceleration changes the direction of velocity in circular motion but not its magnitude.
Answer:
1) a α, m I, W=F.d W =τ . θ,
2) a = v²/r
Explanation:
1) The amounts of rotational and translational motion are related
acceleration is
a = d²x / dt²
linear displacement is equivalent to angular rotation, therefore angular acceleration is
α = d²θ / dt²
force in linear motion is equivalent to moment in endowment motion
F = m a
τ = I α
the mass is the inertia of the translation, in rotational motion the moment of inertia is the rotational inertia
I = m r²
Work is defined by W = F. d
in rotation it is defined by W = τ . θ
The linear momentum is p = mv
the angular momentum L = I w
momentum the linear motion is I = F dt
in the rotation it is I = τ dt
2) The velocity is a vector therefore it has modulus and direction, linear acceleration changes the modulus of velocity, whereas circular motion changes the direction (the other element of the vector).
[tex]a_{c}[/tex]Ac = v²/r
Two kilograms of nitrogen (N2) at 25°C is contained in a 0.62 m3 rigid tank. This tank is connected by a valve to a 0.16 m3 rigid tank containing 0.8 kg of oxygen (O2) at 127°C. The valve is opened, and the gases are allowed to mix, achieving an equilibrium state at 87°C.
initial pressures of N2 is 5.7293 bar and O2 is 5.2 bar.
the final pressure is 6.44 bar.
the magnitude of the heat transfer for the process is 162.8 kJ, and the direction of energy flow is going in.
What is the entropy change for the mixing process, in kJ/K?
Answer:
Explanation:
For entropy change the formula is
ΔS = ΔQ / T
ΔQ = Δ H
ΔS = Δ H / T
Given
Δ H = + 162.8 kJ
We can take equilibrium temperature as average temperature of the whole process
So, T = 273 + 87 = 360 K
ΔS = Δ H / T
= 162.8 kJ / 360
= + 0.508 kJ / K .
When the magnitude of the heat transfer for the process is 162.8 kJ, Then the entropy change for the mixing process, in kJ/K is = + 0.508 kJ / K
What is Entropy change?
For The entropy change, the formula is
Then ΔS = ΔQ / T
After that ΔQ = Δ H
Then ΔS = Δ H / T
Given as per question are:
Then Δ H = + 162.8 kJ
Now We can take equilibrium temperature as average temperature of the whole process are:
So, T is = 273 + 87 = 360 K
Then ΔS = Δ H / T
After that = 162.8 kJ / 360
Therefore, = + 0.508 kJ / K.
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(c) An object of mass 100 kg is accelerated uniformly from a velocity of 15m/s to 20 m/s in 10 s.
Calculate the initial and final momentum of the object.
Also, find the magnitude of the force exerted on the object.
Explanation:
momentum = mass x velocity
initial momentum = 100 x 15 = 1500kgm/s
after momentum = 100 x 20 = 2000kgm/s
a =(v-u)/t
a = (20-15)/10
a = 5/10
a = 0.5m/s²
f = ma
f = 100 x 0.5
f = 50N
The fan on a personal computer draws 0.3 ft3/s ofair at 14.7 psia and 708F through the box containing the CPU and other components. Air leaves at 14.7 psia and 838F.Calculate the electrical power, in kW, dissipatedby the PCcomponents
Answer:
0.12 kW
Explanation:
Given that
The flow rate of air (V)=0.3 ft³/s
V=0.008 m³/s
Pressure, P=14.7 psia
P=1.013529 atm=101.325 kPa
Inlet temperature = 70° F=294.261 K
Exit temperature = 83° F=301.483 K
We know that , specific heat capacity of the air
Cp=1.005 kJ/kg.K
The mass flow rate of air is given as
[tex]\dot{m}=\dfrac{P\times V}{R\times T}\\\dot{m}=\dfrac{101.325\times 0.008}{0.287\times 294.261}\\\dot{m}= 0.0095\ kg/s[/tex]
By using energy conservation
[tex]Electric\ power =\dot{m}\times C_p\times (T_2-T_1)\\Electric\ power =0.0095\times 1.005\times (83-70)=0.12\ kW[/tex]
Therefore electric power dissipate by components will be 0.12 kW.
Did to gravity, the moon has a much smaller acceleration than earth. How do you think that would affect the period of pendulum?
I think any pendulum would swing slower on the moon than it would on Earth.
The time it takes a pendulum to go through a complete back and forth swing is:
Time period = 2 π √(length/gravity)
You can see that 'gravity' is in the denominator of the fraction, so the smaller gravity gets, the longer the period gets.
To be a little bit more technical, the period is inversely proportional to the square root of gravity.
So the period for a complete swing on the moon would be √(9.8/1.6) times as long as the complete swing of the same pendulum on Earth.
That number is roughly 2.47 .
So, for every 1 second that a pendulum takes to swing back and forth once on Earth, the same pendulum would take 2.47 seconds to do it on the moon.
Answer:
based on my opinion....
as we know that gravity in moon are less than gravity in earth.. since the force of gravity is less on the moon, the pendulum would swing slower at the same length, angle
and the frequency would be less.
I hope this helps
HELP me pleaseeee somebody
an object is placed 30cm from a mirror of focal length 15 cm the object is 7.5cm tall. where is the image located? how tall is the image??
Explanation:
It is given that,
Object distance from the mirror, u = -30 cm
Focal length of the mirror, f = +15 cm
Size of the object, h = 7.5 cm
We need to find the image distance and the size of the image.
Mirror's formula, [tex]\dfrac{1}{v}+\dfrac{1}{u}=\dfrac{1}{f}[/tex]
v is image distance
[tex]\dfrac{1}{v}=\dfrac{1}{f}-\dfrac{1}{u}\\\\\dfrac{1}{v}=\dfrac{1}{(15)}-\dfrac{1}{(-30)}\\\\v=10\ cm[/tex]
Let h' is the size of the image. So,
[tex]\dfrac{h'}{h}=\dfrac{-v}{u}\\\\h'=\dfrac{-vh}{u}\\\\h'=\dfrac{-10\times 7.5}{-30}\\\\h'=2.5\ cm[/tex]
So, the image is located at a distance of 10 cm and the size of the image is 2.5 cm.
formula of minimmum pressure
Answer:
pressure=force/area
1. The electric field strength between two parallel plates separated by 6.00 cm is 7.50 × 104 V/m . (a) What is the potential difference between the plates? (b) The plate with the lowest potential is taken to be zero volts. What is the potential 1.00 cm from that plate and 6.00 cm from the other?
Answer:
a)4500V
b)750V
Explanation:
Given:
Distance between the plate=
6.00 cm
We need to convert to m
Then the Distance between the plate=
0.06m
electric field strength between two parallel plates =
7.50 × 104 V/m .
Then E= 7.50 × 104 V/m .
(a) What is the potential difference between the plates?
potential difference between the plates can be calculated using the formula below
Δ Vab=ED
Where E is the given electric field strength
D= The Distance between the plate
ΔVab=7.50 × 10⁴V/m ×
0.06m
= 4500V
(b) The plate with the lowest potential is taken to be zero volts. What is the potential 1.00 cm from that plate and 6.00 cm from the other?
the potential 1cm from the zero volt plate
Then the 1cm must be converted to m
= 0.01m
Let us say plate A as the plate at 0 volts:
The potential increases linearly going from plate A (0 V) to plate B (4500V).
Therefore,if the potential difference between A and B, separated by 6 cm, is 4500 V, then the potential difference between A and a point located at 1 cm from A is can be calculated also
If the plate with Lowest potential is taken to be zero then
=ΔVab=Vab-Vb=Va-0=Va=ED
Va=7.50 × 10⁴V/m × 0.01=750V
What is the magnitude of the gravitational force between the earth and a 1 kg object on its surface? (Mass of the earth is 6 × 10 24 kg and radius of the earth is 6.4 × 10 6 m.)
Answer:
Explanation:
just use the gravational force equation which is G x m of earth x m of object divided by r squared (which is radius of earth)
To a stationary observer, a bus moves south with a speed of 12 m/s. A man
inside walks toward the back of the bus with a speed of 0.5 m/s relative to
the bus. What is the velocity of the man according to a stationary observer?
A. 11 m/s south
B. 12.5 m/s south
C. 11.5 m/s south
D. 0.5 m/s south
ANSWER
C 11.5 m/s
EXPLANATION
Answer:
11.5m/s south
Explanation:
Online classes
A carpenter measured the lengeth of a small piece of timber as 24.6cm .Calculate the relative error in the measurement if the true length is 24.5cm
ANSWER:
0.4081%
Explanation:
Difference=24.6-24.5=0.1
Relative error = 0.1/24.5*100=0.4081%
Relative error is equal to the = difference between both the values/The true value *100
Please help asap. A soccer player can kick a 0.370 kg football at 55 km/h. How much work does the soccer player have to do on the ball in order to give it that much kinetic energy?
Answer: 43.2 J
Explanation:
Work = change in KE
initial KE = 0
final KE = 1/2mv^2 = 1/2(0.370 kg)(15.2778 m/s)^2 = 43.2 J
i'm not sure about sig figs though
The total mass of eight identical
building blocks is 31.52 kg. Find the
mass of 1 block.
Answer:
3.94
Explanation:
divide total mass by the number of blocks since they are identical
Answer:
3.94
Explanation:
You want to find the mass of one block. Since we know there is 8 blocks with the same mass, you can divide the total mass by 8 since the mass is equally distributed within the 8 blocks
3.) [15 points] A physics teacher is on the west side of a small lake and wants to swim across and up at a point directly across from his starting point. He notices that there is a current in the lake and
that a leaf floating by him travels 4.2m [S] In 5.0s. He is able to swim 1.9 m/s in calm water,
(a) What direction will he have to swim in order to arrive at a point directly across from his position?
Answer:
The teacher should swim in a direction 29.24° North of East
Explanation:
Given that the there is a water current across the lake, and the physics teacher intends to swim directly across the lake, the direction the physics teacher will have to swim is found as follows;
The speed of the water current is given by the speed of the floating leaf traveling with the water current
Distance traveled by the leaf = 4.2 m South
Time of travel of the leaf = 5.0 s
Speed of leaf = 4.2/5 = 0.84 m/s = Speed of the water current
Swimming peed of the teacher, v = 1.9 m/s
To swim directly across the lake, the teacher has to swim slightly in the opposite direction of the water current, the y-component of the teacher's swimming speed should be equal to and opposite that of the speed of the water current.
Y-component of v = v×sin(θ), where θ is the angle of the direction, the teacher should swim
Therefore;
1.9 × sin(θ) = 0.84
sin(θ) = 0.84/1.9 = 0.44
θ = 26.24°
That is the teacher should swim in a direction 29.24° North of East.
To cross the lake the teacher has to swim in a direction 29.24° North of the East
Finding the direction of speed required:
The speed of the water current can be derived from the speed of the floating leaf :
The distance traveled by the leaf L = 4.2 m South
Time taken T = 5s
So, the speed of the leaf is:
u = 4.2/5
u = 0.84 m/s South
So, the speed of the current is 0.84 m/s South
Now, it is given that the speed of the teacher is, v = 1.9 m/s East
To cross the lake the speed of the teacher must be in a Northeast direction so that the North component of the speed of the teacher cancels out the speed of the current which is directed towards the South.
Let, the speed of the teacher makes an angle of θ from the EAST.
So, the North component is given by:
v(north) = vsinθ
it must be equal to the speed of the current:
vsinθ = u
1.9 × sinθ = 0.84
sinθ = 0.84/1.9
sinθ = 0.44
θ = 26.24°
The teacher should swim in a direction 29.24° North of East.
Learn more about vector components:
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A 140-Hz sound travels through pure carbon dioxide. The wavelength of the sound is measured to be 1.92 m. What is the speed of sound in carbon dioxide?
Answer:
V = 268.8 m/s
Explanation:
The speed of a wave in general is given by the following formula:
V = fλ
where,
V = Speed of that wave
f = Frequency of the wave
λ = wavelength of the wave
In this case we have a sound wave, travelling across carbon dioxide. The properties of sound wave are as follows:
V = Speed of Sound in Carbon dioxide = ?
f = frequency of sound wave = 140 Hz
λ = wavelength of sound wave = 1.92 m
Therefore,
V = (140 Hz)(1.92 m)
V = 268.8 m/s
A load of 500N is carried by 200N effort in a simple machine having load distance 3m Calculate effort distance.
Answer:
2.5 mExplanation:
Load ( L ) = 500 N
Effort ( E ) = 200 N
Load distance ( LD ) = 3 m
Effort distance ( ED ) = ?
Now, Let's find the Effort distance ( ED )
We know that,
Output work = Input work
i.e L × LD = E × ED
plug the values
[tex]500 \times 3 = 200 \times ED[/tex]
multiply the numbers
[tex]1500 = 200 \times ED[/tex]
Swipe the sides of the equation
[tex]200 \: ED \: = 500[/tex]
Divide both sides of the equation by 200
[tex] \frac{200 \: ED}{200} = \frac{500}{200} [/tex]
Calculate
[tex]ED\: = 2.5 \: m[/tex]
Hope this helps..
best regards!!
A physics professor uses an air-track cart of mass m to compress a spring of constant k by an amount x from its equilibrium length. The air-track has negligible friction. When she lets go, the spring launches the cart. What cart velocity should she expect after it is launched by the spring
Answer:
v = √k/m x
Explanation:
We can solve this exercise using the energy conservation relationships
starting point. Fully compressed spring
Em₀ = [tex]K_{e}[/tex] = ½ k x²
final point. Cart after leaving the spring
[tex]Em_{f}[/tex] = K = ½ m v²
Em₀ = Em_{f}
½ k x² = ½ m v²
v = √k/m x
PLEASE HELP ASAP. IT'S URGENT
Answer:
Q1 acceleration = 16m/s²
Q2 Net force = 9N North
Explanation:
Q1 Using the formula F=ma
Q2 R = F1 + F2
Question 21 of 25
Barry slides across an icy pond. The coefficient of kinetic friction between his
shoes and the ice is 0.15. If his mass is 83 kg, what is the force of friction
acting on him
O A 352 N
O B. 122 N
C. 1150 N
O D. 813N
Answer:
B. 122N
Explanation:
f = 0.15 x 83 x 9.8 = 122.01
f = 122N
A wall in a house contains a single window. The window consists of a single pane of glass whose area is 0.15 m2 and whose thickness is 7 mm. Treat the wall as a slab of the insulating material Styrofoam whose area and thickness are 17 m2 and 0.20 m, respectively. Heat is lost via conduction through the wall and the window. The temperature difference between the inside and outside is the same for the wall and the window. Of the total heat lost by the wall and the window, what is the percentage lost by the window
Answer:
88 %
Explanation:
The rate of heat loss by a conducting material of thermal conductivity K, cross-sectional area,A and thickness d with a temperature gradient ΔT is given by
P = KAΔT/d
The total heat lost by the styrofoam wall is P₁ = K₁A₁ΔT₁/d₁ where K₁ =thermal conductivity of styrofoam wall 0.033 W/m-K, A₁ = area of styrofoam wall = 17 m², ΔT₁ = temperature gradient between inside and outside of the wall and d₁ = thickness of styrofoam wall = 0.20 m
The total heat lost by the glass window is P₂ = K₂A₂ΔT₂/d₂ where K₂ =thermal conductivity of glass window pane wall 0.96 W/m-K, A₂ = area of glass window pane = 0.15 m², ΔT₂ = temperature gradient between inside and outside of the window and d₂ = thickness of glass window pane = 7 mm = 0.007 m
The total heat lost is P = P₁ + P₂ = K₁A₁ΔT₁/d₁ + K₂A₂ΔT₂/d₂
Now, since the temperatures of both inside and outside of both window and wall are the same, ΔT₁ = ΔT₂ = ΔT
So, P = K₁A₁ΔT/d₁ + K₂A₂ΔT/d₂
Since P₂ = K₂A₂ΔT₂/d₂ = K₂A₂ΔT/d₂is the heat lost by the window, the fraction of the heat lost by the window from the total heat lost is
P₂/P = K₂A₂ΔT/d₂ ÷ (K₁A₁ΔT/d₁ + K₂A₂ΔT/d₂)
= 1/(K₁A₁ΔT/d₁÷K₂A₂ΔT/d₂ + 1)
= 1/(K₁A₁d₂÷K₂A₂d₁ + 1)
= 1/[(0.033 W/m-K × 17 m² × 0.007 m ÷ 0.96 W/m-K × 0.15 m² × 0.20 m) + 1]
= 1/(0.003927/0.0288 + 1)
= 1/(0.1364 + 1)
= 1/1.1364
= 0.88.
The percentage is thus P₂/P × 100 % = 0.88 × 100 % = 88 %
The percentage of heat lost by window of the total heat is 88 %
A very thin film of soap, of thickness 170 nm, in between air seems dark. On the other hand, when placed on top of glass some visible light is seen to shine from the film. How can this happen and what is the smallest visible light that creates constructive interference when we place the film on top of glass
Answer:
λ₀ = 2 d n
Explanation:
A soap film is a layer where the lus is reflected on the surface and on the inside of the film, these two reflected rays can interfere with each other either constructively or destructively.
Let's analyze the general conditions of this interference,
* When the ray of light reaches the surface of the film it is reflected, as the index of refraction of the air is less than the index of the film, the reflected ray has a phase change of 180º
* When the ray penetrates the film, its wavelength changes due to the refractive index of the film.
λ = λ₀ / n
where lick is the wavelength in the vacuum or air and n index of refraction of the film, in general this interference is observed perpendicular to the film, so the sine veils 1. the expression for constructive interference taking in what previous remains
2d = (m + ½) λ
the expression for destructive interference remains
2d = m λ
2d = m λ₀ / n
When the film is placed on a glass plate whose index of refraction is greater than the index of refraction of the film, in the reflection in the lower part of the film another phase difference of 180º is created, for which we have a difference of total phase of 180 +180 = 360º, which is equivalent to no phase difference, therefore the two previous equations are interchanged.
Therefore where we had destructive interference now a cosntructive interference happens we can see the reflected light.
Find us the wavelength that this constructive interference creates
2d n = m λ₀
λ₀ = 2 d n / m
To find the minimum wavelength, suppose we observe the first interference pattern m = 1
λ₀ = 2 d n
where d is the thickness of the film and n the index of refraction of the same