Answer:
The contribution of the wavelets lying on the back of the wave front is zero because of something known as the Obliquity Factor. It is assumed that the amplitude of the secondary wavelets is not independent of the direction of propagation, Sources: byju's.com
According to the Voigt and Kirchhoff's law for wavelets, the contribution of a wavelet in any direction making an angle x with the normal to the wavelet is proportional to {1+cos(x)/2)}
For wavelet lying on the back of secondary wavefront,
x = 180°→ So, the proportional factor:
→ {1+cos(180°)/2}
→ (1-1/2)
→ (0/2)
→ 0
That's why the contribution of the wavelets lying on the back of secondary wave front is zero
Einstein published three major scientific papers. One of these put forward a new way of calculating the size of molecules. Another explained Brownian motion — the random dance performed by specks of dust trapped in a fluid. Einstein suggested that the tiny particles making up the fluid — its atoms or molecules — were bouncing against the specks of dust and causing the motion. These papers helped to establish the reality of atoms and molecules. Another of Einstein’s 1905 papers explained the photoelectric effect — the way that metals could emit electrons (tiny charged particles) from their surface when light was shone on them. Most scientists believed that light travelled in waves — like sound or water waves. But Einstein suggested that the photoelectric effect could be explained if light could also behave as a stream of tiny packets of energy.
(2) Einstein’s paper on the photoelectric effect helped give birth to quantum theory, and it was for this paper that Einstein received the Nobel Prize in 1922. Quantum theory led, in the 1920s and 1930s, to another revolution in physics. Physicists showed that, as well as light waves behaving like particles, particles could sometimes act as waves. This theory established “objective probability” in physics. This was the idea that completely unpredictable chance events can take place at the subatomic level. Einstein never fully accepted the prevalent interpretation of quantum theory. But, while many of these interpretations involve wild metaphysical flights of fancy, the physical results are, like those of relativity, very well established.
(3) Marrying together the two pillars of 20th century physics — relativity and quantum theory — is a central problem for physics even today. Successfully doing this may require a revolution in science similar to those begun by Newton and Einstein. There are three main interconnected driving forces for such changes in science. The first is the development of technology. Changes in technology can make new experiments possible and they also influence the problems that scientists develop an interest in. Newton was fascinated by the new machines of the 17th century. Similarly, Einstein was fascinated by electricity and magnetism. This influence also works in a negative way. The governments and multinationals that control technology are often able to dictate what is researched.
(4) The second factor driving scientific progress is the way that the dominant ideas in society change. Ideas from the broader culture can impinge upon science. Newton’s ideas were part of a revolutionary new attempt at a rational explanation of both nature and society. On the other hand, the dominant ideas in society can also limit the development of science. This is most obvious in the social sciences, where delving too deeply into how society is organized might raise difficult questions for our rulers. Less is at stake in the natural sciences. Indeed, improvements in natural sciences are vital to our rulers if they want to compete effectively with each other. But the distorted worldview of capitalism still impacts on science. Extremely narrow and specialized bodies of knowledge develop—creating problems for scientists trying to bring about the kind of sweeping revolution heralded by Einstein.
(5) Finally, science moves forward because scientists seek to develop logically consistent theories. This can push them beyond the dominant or common sense ideas of their time. Einstein’s breakthrough cannot be reduced simply to changes in technology or wider cultural and ideological shifts. Science is not simply the gathering and ordering of data about the outside world. It also requires abstraction—developing theories about the underlying laws of nature that are usually not immediately apparent. This crucial role of theory is not just a feature of the natural sciences.
(6) Einstein argued that “common sense is the prejudices acquired by age 18”. Marxist theory, which is a social science topic, challenges “common sense” political ideas. If we, according to this theory, want to change the world, we need to combine our actions with theory that digs below the surface appearance of society to understand how the system works.What is the writer’s point of view?
For the author, science is a field that does not just require the collection and ordering of data about the outside world.
According to the text, science must also be the development of theories about the invisible and non-apparent laws of nature.
What factors drive scientific progress?For the author, progress is related to the development of technology, the cultural ideas of society, which change over time, and the logical theories that are developed by scientists.
Therefore, the author proposes a reflection on the challenges of the development of science in today's society, according to the two pillars of physics, which are relativity and quantum theory.
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3. When are ionic compounds able to conduct electricity?
Ionic compounds conduct electricity when molten (liquid) or in aqueous solution (dissolved in water), because their ions are free to move from place to place. Ionic compounds cannot conduct electricity when solid, as their ions are held in fixed positions and cannot move.
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A car travels 310 miles in 6. hours. How far will it go in 8 hours at this average
velocity?
Pls show work
Answer:
413
Explanation:
first i divided 310 by 6 which equals 51.66 and then i times it by 8 which equals 413.33 and you perbulby are going to round ot so it would by just 413
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3. Specify the wrong sentences.
a) young stars at this stage are called red giant. True/False
b) The stars go to the end of their lives by turning most of their hydrogen into helium. True/False
c) Helium sink inside the star, causing its temperature to rise and swelling on the outside, thus extending it. These stars "swollen (puffy)" are known as Supernova. True/False
Answer:
a: false
b: True
c: i dont know
Explanation:
Which of the following would cause the greatest increase in gravitational
force between two objects?
OA. Reducing the mass of one object by half
OB. Doubling the mass of one object
OC. Doubling the distance between the objects
D. Halving the distance between the two objects
Explanation:
To be honest, it depends how far away the object is. half of 2 is 1, half of 1000000 is 500000 soo, but I would say doubling the mass.
The Shanghai World Financial Center is one of the tallest buildings in the world. It features a large trapezoidal opening to allow wind to pass through. The opening is about 35 meters tall. It is about 40 meters along the bottom and 50 meters along the top. What is the approximate area of the opening?
The approximate area of the trapezoidal opening allow wind to pass through is 1575 m².
What is the area of trapezium?The area of the trapezium is the product of height and mean of the top and bottom side of trapezium.
Given is the height h = 35m, the base a =40 m and top b = 50m, then the area of the trapezium is
A = (a +b / 2) x h
Substitute the value into the expression, we get
A = (40 +50/2) x 35
A = 1575 m²
Thus, the approximate area of the trapezium is 1575 m².
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A ball of mass 50 g is suspended at a height of 2.5 m from the ground. In terms of the gravitational
potential energy (GPE) and kinetic energy (KE) of the ball, which of the following statements is
correct?
A GPE is maximum, KE is 0
B. KE is maximum, GPE is 0
C. GPE = KE at this point
D. the ball has no GPE
Answer:
A
Explanation:
Finding Gravitational Potential Energy :
GPE = mass x gravitational acceleration x height
GPE = 50 x 10⁻² x 10 x 2.5GPE = 5 x 2.5GPE = 12.5 JFinding Kinetic Energy :
KE = 1/2 x mass x (velocity)²
KE = 1/2 x 5 x 10⁻² x (0)²KE = 0Hence, option A is correct.
Indicate the North Pole and the direction of the current in each of the wires below.
Answer:
Explanation Draw a diagram showing the direction of the magnetic field lines due to a straight wire carrying current. Also show the direction of current in the wire.When electric current flows through a conductor, an induced EMF is created which in turn creates a magnetic field around it. The magnetic field lines form concentric circles around the conductor. The direction of the magnetic field is perpendicular to the wire and is in the direction of wrapped fingers of the right hand holding the conductor and the thumb pointing upwards indicates the direction of the current.
A magnetic field implies the existence of poles and the polarity of a current carrying conductor is north-south when the current flows in the anti-clockwise direction. When magnetic compass with the north end is brought closer to the 1st end of the conductor, the needle deflects towards the west, that is away from the conductor because the magnetic compass that is pointing in the direction of the earth's magnetic field, i.e. north- south direction repels with the north pole of current carrying conductor. Like poles repel each other. This is the fundamental principle of magnetism.
The North Pole of a magnet is the end that points towards the Earth's magnetic North Pole.
In terms of current flow, the direction of the current in a wire is determined by the flow of positive charge. To indicate the North Pole and the direction of the current in each of the wires below, we can use the right-hand rule. Here's how it works:
1. Hold the wire in your right hand with your thumb pointing in the direction of the current flow (from positive to negative).
2. Curl your fingers around the wire. The direction in which your fingers curl represents the direction of the magnetic field created by the current. 3. The direction in which your thumb points represents the North Pole of the magnet. Let's apply this rule to the wires below: Wire 1: - If the current flows from left to right in wire 1, then your thumb points to the right, indicating the North Pole of the magnet.
Wire 2: - If the current flows from top to bottom in wire 2, then your thumb points downwards, indicating the North Pole of the magnet. Wire 3: - If the current flows from right to left in wire 3, then your thumb points to the left, indicating the North Pole of the magnet. Remember, the direction of the current flow can be reversed, which would also reverse the direction of the magnetic field and the indication of the North Pole. By using the right-hand rule, you can determine the direction of the current and identify the North Pole of a magnet in a wire.
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A 5OKG mass is taken to the moon and the mass determined there, comment on the likely result of the measurement
Answer:
Mass will be the same
Explanation:
Mass does not change with gravity .... WEIGHT will be different, but not mass.
What is the typical magnification of an ocular lens? what other magnifications are possible?.
Your scope's ocular lenses have a magnification of 10X. Magnification typically falls between 10x and 1,000x, with some versions even going up to 2000x.
What is magnification?
Magnification refers to the image's size in relation to the item that produced it.
The ratio of image length to object length, measured in planes perpendicular to the optical axis, is referred to as linear magnification.
For imaging, optical microscopes combine ocular and objective lenses. The sum of the magnifying powers of the individual lenses produces the observation magnifying power.
This typically falls between 10x and 1,000x, with some versions even going up to 2000x.
Hence, the ocular lenses of your scope are 10X magnified and magnification usually ranges from 10x to 1,000x, while some versions can reach 2000x.
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Mr. Mock sets up a demonstration on a moving bus. The device consists of a ball attached with a string to a magnet. He uses the magnet to hang the ball from the top of the school bus as the bus turns the corner at a constant speed. What will the ball do?
A) Nothing changes.
B) The ball rolls forward slowly.
C) The ball rolls forward rapidly.
D) The ball rolls backward.
When the bus turns the corner at a constant speed, the velocity of the ball will change and the ball will rolls forward slowly.
Motion of an object at constant speed
The speed of an object is defined by magnitude only while the velocity of an object is defined by both magnitude and direction.
Suffice it to say that when an object is moving at a constant speed changes direction, its velocity will change.
Velocity of ballThe velocity of the ball can be determined by modelling the speed of the car in the bend or corner.
v = √μrg
where;
μ is coefficient of frictionr is radius of the cornerg is gravitySince the velocity of the bus changes, the velocity of the ball will change.
Thus, when the bus turns the corner at a constant speed, the velocity of the ball will change and the ball will rolls forward slowly due to magnetic force acting as resistive force.
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What is ima of the
doorknob
Answer:
ima of the doornob is a show. they have a movie secires too
Explanation:
If a car accelerates at 6.4 m/s?
1, what will its velocity be after 9.0
seconds? (Answer to 1 decimal place)
Final velocity be v
According to first equation of kinematics
v=u+atv=0+6.4(6)v=57.6m/sA rock dropped down a well takes 2.5 seconds to hit the water. How far below the
top of the well is the surface of the water? [Answer to 1 decimal place)
Answer:
30.6 m
Explanation:
Given:
v₀ = 0 m/s
a = 9.8 m/s²
t = 2.5 s
Find: Δy
Δy = v₀ t + ½ at²
Δy = (0 m/s) (2.5 s) + ½ (9.8 m/s²) (2.5 s)²
Δy = 30.6 m
A car travels a distance of 200 miles in 3.5 hours in a given trip. What is the average speed of the car in that
trip? Write the data given, equation, substitution and the answer with correct units for full credit.
Taking into account the definition of speed, the average speed of the car in the trip is 57.14 [tex]\frac{miles}{hour}[/tex].
Definition of speedSpeed is a physical magnitude that relates the displacement of an object and the time it takes to make this change in position.
So, the speed can be defined as the amount of space traveled per unit of time with which a body moves and can be calculated using the expression:
[tex]speed=\frac{displacement}{time}[/tex]
Speed has units of [tex]\frac{distance}{time}[/tex], such as [tex]\frac{meters}{second}[/tex] or [tex]\frac{miles}{hour}[/tex].
Average speed of the carIn this case, you know that:
displacement= 200 milestime= 3.5 hoursReplacing in the definition of speed:
[tex]speed=\frac{200 miles}{3.5 hours}[/tex]
speed= 57.14 [tex]\frac{miles}{hour}[/tex]
Finally, the average speed of the car in the trip is 57.14 [tex]\frac{miles}{hour}[/tex].
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Question: What are phases of the moon. What evidence can you provide to explain how the moon revolution determines its shape?
Think!!!! Write Claim, Reasoning and add evidence
Answer:
Claim: The phases of the Moon progress from new moon to crescent moon, first-quarter moon, gibbous moon, and full moon as the Moon waxes (the amount of illumination is increasing from Earth). As the moon revolves around Earth, its sunlit surface is visible in different portions as it reveals its phases.
Evidence: As the moon revolves around Earth, different parts of the sunlit surface of the moon can be seen. As a result, the moon's appearance changes from night to night from Earth's perspective. The moon's apparent shape changes, as well as its position in the sky.
Reasoning: Over the course of two weeks, the moon's entire appearance changes, from a bright circle to a circle sliced in half and finally to nothing.
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Answer:
Claim: The phases of the Moon progress from new moon to crescent moon, first-quarter moon, gibbous moon, and full moon as the Moon waxes (the amount of illumination is increasing from Earth). As the moon revolves around Earth, its sunlit surface is visible in different portions as it reveals its phases.
Evidence: As the moon revolves around Earth, different parts of the sunlit surface of the moon can be seen. As a result, the moon's appearance changes from night to night from Earth's perspective. The moon's apparent shape changes, as well as its position in the sky.
Reasoning: Over the course of two weeks, the moon's entire appearance changes, from a bright circle to a circle sliced in half and finally to nothing.
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During radioactive beta-decay, a neutron (1.6749x10-27 kg) at rest decays into a very slow moving proton (1.6726x10-27 kg) and a fast electron (9.109x10-31 kg). What is the speed of the electron? (Hint: find the total energy of the electron)
The speed of the electron emitted in the radioactive beta-decay is determined as 2.186 x 10⁶ m/s.
Speed of electronThe speed of the electron is determined from the total energy of the electron.
Assuming the emitted electrons are in first energy level, E = 13.6 eV
K.E = ¹/₂mv²
v² = 2K.E/m
v² = (2 x 13.6 x 1.6 x 10⁻¹⁹)/(9.11 x 10⁻³¹)
v² = 4.777 x 10⁻¹²
v = 2.186 x 10⁶ m/s
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Describe the mechanisms by which out-of-plane deformation in the laser forming
process can occur. As part of your answer, identify the mechanism of laser forming
which is active for the experimental results provided.
The mechanisms by which out-of-plane deformation in the laser forming process can occur include:
Temperature gradient mechanismBuckling mechanismUpsetting mechanism.What is Temperature gradient mechanism?This is the mechanism which involves bending the sheet to a laser light source.
The experiment shown in this scenario depicts it as one plane of the sheet can be seen raised.
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A force of 77 N is used to move a desk 1.5 m. How much work was done?
A. 75.2 J
B. 121.0 J
C. 115.5 J
D. 51.3 J
Answer:
As we know,
work = 77 N × 1.5m
therefore 115.5 J work was done
Calculate the force on a unit positive charge at p on x axis whose co-ordinates are (x=2m,y=0) due to the following two charges 1. A positive charge of 10−9C situated in air at the origin (X=0,y=0). 2. A negative charge of -2*10−9C situated on X axis(x=1m, y=0
The force on a unit positive charge at the given position is determined as 1.8 x 10⁻⁸ N.
Force on the chargeThe force on the charge is calculated as follows;
F = k(q1q2)/r²
where;
r is the distance between the charges = 2 m - 1m = 1mF = (9 x 10⁹ x 10⁻⁹ x 2 x 10⁻⁹)/(1)²
F = 1.8 x 10⁻⁸ N
Thus, the force on a unit positive charge at the given position is determined as 1.8 x 10⁻⁸ N.
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Erwin Schrödinger developed the quantum model of the atom. What scientific knowledge was necessary for Schrödinger’s work?
Answer:
Erwin Schrödinger developed the quantum model of the atom. What scientific knowledge was necessary for Schrödinger's work? The discovery of the electron.
Explanation:
how many components can be realized of a vector?
Answer:
two different components
Explanation:
Any two-dimensional vector can be conceived of as having two distinct components. The component of a single vector describes the vector's effect in a specific direction.
why does light reflecting off of a piece of paper get scattered in all directions even though it appears to be flat and smooth? (be sure to include the idea of the normal line in your explanation)
Answer:
If light meets a rough surface, each ray obeys the law of reflection. However, the different parts of the rough surface point in different directions, so the light is not all reflected in one direction. Instead, the light is reflected in all directions. This is called diffuse scattering
Explanation:
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What kind of weather ,begin emphasis,most,end emphasis, likely happens in the town when the air masses meet?
Storm weather likely happens in the town when the air masses meet because of difference of temperature and humidity of both air masses.
What weather happens when air masses meet?
When air masses move by wind, they carry different weather conditions from the weather conditions of other region. This difference in weather conditions can create a severe storm.
So we can conclude that Storm weather likely happens in the town when the air masses meet because of difference of temperature and humidity of both air masses.
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CFCs were found to destroy what important compound in our atmosphere?
CFCs were found to destroy the important compound in our atmosphere which is called as the Ozone layer.
What are CFCs?The CFCs are called as the Chloro Fluoro carbon are the fuels used in the jet flights long time ago.
The ozone layer protects the harmful UV rays coming from the Sun to reach the Earth's surface. This layer was depleted by the use of CFCs which consist of harmful element Chlorine in large amount.
This has developed a hole in ozone layer over Antarctica. Global warming is the greatest consequence of the depletion of ozone layer.
Thus, CFCs found to destroy ozone layer.
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If two balls have the same volume, but ball A has twice as much mass as ball B, which one will have the greater density?
Answer:
A
Explanation:
Density is mass/ volume
if the numerator is greater ( A) then the density is greater than B
an object is dropped from a height of 25 meters.at what velocity will it hit the ground?
a.)7.0 m/s
b.)11 m/s
c.)22m/s
d.) 49 m/s
e.) 70 m/s
Answer:
C. 22 m/s
Explanation:
Ignoring air friction....all of the Potential energy will be converted to Kinetic Energy
mgh = 1/2 m ^v^2
gh = 1/2 v^2
sqrt (2 gh) = v = ~ 22.1 m/s
Describe how you come in direct contact with at least 5 of the 7 areas of the electromagnetic spectrum each day.
Answer:
Color, Radio Waves, Infrared Waves, Ultraviolet waves and Micro waves
Explanation:
you see color every day, radio signals are all around you, thats how you hear music in you car by radio, IR and UV waves both come from the sun that literally touches your skin(sun burn and tanning) and all of the waves come from the sun, you interact with a micro wave every day if you have a micro wave that uses micro waves to cook food in your microwave hence the name
What is the velocity of an object that has been in free fall for 2.5 s?
A. -3.9 m/s downward
B. 3.9 m/s downward
C. 250 m/s downward
O
D. 25 m/s downward
After 2.5 seconds of free fall, an item will be moving downhill at a speed of 25 m/s.Option D is correct.
What is velocity?The change of displacement with respect to time is defined as speed. Speed is a scalar quantity. It is a time-based component. Its unit is m/sec.
The given data in the problem is;
t(time)= 2.5 s
u(falling velocity)=0 m/sec
v(striking velocity)=? (m/sec)
Newton's first equation of motion:
v=u+at
v=u+gt
v=10 × 2.5
v= 25 m/s downward(+ ve taken as downward)
The velocity of an object that has been in free fall for 2.5 s will be 25 m/s downward.
Hence, option D is correct.
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A jogger has an average stride length of 140 cm and takes an average of 200 steps per minute. The jogger's average speed would be
From the calculations, the speed of the jogger is calculated as 4.7 m/s.
What is speed?The term speed refers to the ratio of distance covered to time taken. In this case we know that;
steps per minute = 200 steps per minute.
1 stride length = 140 cm
Distance covered in 200 strides = 200 * 140 = 28000 cm or 280 m
time taken = 1 minute or 60 seconds
Speed of the jogger = 280 m/60 seconds = 4.7 m/s
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