Answer:
the cell is the smallest unit
Why is the contribution of the wavelets lying on the back of secondary wave front zero?
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
A sewing machine uses 1.6kWh of electricity in one day. If electricity costs 9p per unit, what is the total cost in pence of using the sewing machine that day? Give your answer to 3 significant figures.
Answer:
[tex]\huge\boxed{\sf 1.6\ units = 14.4p}[/tex]
Explanation:
Since,
1 kWh = 1 unitSo,
1.6 kWh = 1.6 units
If,
1 unit = 9p1.6 units = 9p × 1.6
1.6 units = 14.4p
[tex]\rule[225]{225}{2}[/tex]
I need help with this question (open-ended question) 50 points (NO BOTS!!!)
Choose TWO locations below (A, B, C) and provide a two-sentence weather forecast for that location. Your forecast must include Wind direction, general wind speed (high, moderate, low) general temperatures (cold, cool, mild, warm, hot), and sky conditions(precipitation/stormy, sunny cloudy).
The weather forecast for the locations includes:
London - 21°C°, Precipitation: 60%, Humidity: 79%, Wind: 11 km/h.
New York - 26°C°, Precipitation: 50%, Humidity: 76%, Wind: 19 km/h.
What is weather?It should be noted that weather is the state of the atmosphere with respect to heat or cold, calm or storm, clearness or cloudiness.
Weather forecast is an analysis of the state of the weather in an area with an assessment of the likely developments.
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3. Two wires increase in length by the same amount when both their temperatures increase by the same amount, as shown in the diagram. Before the temperature increase, the longer wire is 1.2525 m long. The shorter wire’s linear coefficient of thermal expansion is 1.135 times that of the longer wire. How much shorter is the shorter wire before the temperature increase? Answer to three significant figures
Viết cho Ngọc Khánh
Two wires increase in length by the same amount when both their temperatures increase by the same amount, the shortness of the wire before the temperature increase is mathematically given as
dL=0.1485m
How much shorter is the shorter wire before the temperature increase?Generally, the equation for change in length is mathematically given as
[tex]dl=lo \alpha dt[/tex]
Therefore
dl1=dl2
Where
a2=1.35a1
Hence
a1l1dt= a2l2dt
a1(1.2525)= a1*(1.135)(l2)
L2=1.104m
In conclusion, a change in length due to temperature is
dL=1.2525-1.104m
dL=0.1485m
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Study the image.
Which of the following choices best explains how the lever made the task easier?
The final force on the rock was the same as the original force from the person and the distance the rock traveled was smaller than the original distance the lever moved, so the total work decreased.
The final force on the rock was greater than the original force from the person and the distance the rock traveled was smaller than the original distance the lever moved, but the total work remained the same.
The final force on the rock was smaller than the original force from the person and the distance the rock traveled was greater than the original distance the lever moved, so the total work stayed the same.
The final force on the rock was greater than the original force from the person and the distance the rock traveled was the same as the original distance the lever moved, so the total work increased.
The final force on the rock was smaller than the original force from the person and the distance the rock traveled was greater than the original distance the lever moved, so the total work stayed the same.
What is the law of conservation of energy?The law of conservation of energy states that energy can neither be created nor destroyed but can be transformed from one form to another.
The total work done on the process will be conserved.
The lever is a simple machine which makes work easier by reducing the force applied to the load and increasing the distance traveled by the load.
Thus, the final force on the rock was smaller than the original force from the person and the distance the rock traveled was greater than the original distance the lever moved, so the total work stayed the same.
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when solving for t you used sin theta instead of cos theta?
Looking out from a vertex with angle θ, sin(θ) is the ratio of the opposite side to the hypotenuse , while cos(θ) is the ratio of the adjacent side to the hypotenuse . No matter the size of the triangle, the values of sin(θ) and cos(θ) are the same for a given θ, as illustrated below.
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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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Is the following chemical reaction balanced?
2H₂O2H₂O + 0₂
yes
no
sketch an electric field pattern around two identical negative point charges shown below in the figure of class 11 model question physics.
Answer:
fv nfv f n f vjrkfv frnv thrfn htrfn vt
Explanation:
v ntv tfrv tn vtv jr4v t5o vtv tv tv
Mr smith needs to put the paving stone dosnt to rest his arms. He does not want the paving stone to sink deep into the mud . Explain which surface of the stone he should put on the ground.
The surface of the stone which he should put on the ground is the base.
What is a Base?This is defined as the flat end which is usually located at the bottom with a larger surface area.
The large surface area helps to distribute the forces on all parts thereby preventing it from sinking.
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which two forces operate over only very SHORT distances?
A. weak nuclear and gravitational
B. strong nuclear and gravitational
C. weak nuclear and electromagnetic
D. strong nuclear and weak nuclear
Strong nuclear and weak nuclear forces act only over short range distances.
What are forces?Forces are agents which bring about a change in the state or motion of an object.
Forces can be described as pull or push agents.
Forces can either be contact or non-contact forces.
Some non-contact forces are gravitational forces and nuclear forces.
Nuclear forces act only over short range distances. Example are the strong and weak nuclear forces.
Therefore, strong nuclear and weak nuclear forces act only over short range distances.
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Discuss how wind energy was used in ancient times.
Answer:
People used wind energy to propel boats along the Nile River as early as 5,000 BC. By 200 BC, simple wind-powered water pumps were used in China, and windmills with woven-reed blades were grinding grain in Persia and the Middle East.
Explanation:
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have a good day
Why is the human population unique in its ability to affect the environment?
Our population is very large.
We use a lot of resources.
Our population is growing quickly.
All of the above.
Subect: science (not sure if this means pyhsics or chemistry)
Answer:
All of the above
Explanation:
hope it helps you
Three sticks are arranged to form a right triangle. If the lengths of the three sticks are 0.47 m, 0.62 m and 0.78 m, what are the three angles of the triangle?
The angles in the triangle are 91 degrees, 53 degrees and 36 degrees respectively.
What is the cosine rule?From the cosine rule we know that;
c^2 = a^2 + b^2 - 2abcosC
Since;
a = 0.47 m
b = 0.62 m
c = 0.78 m
Then;
(0.78)^2 = (0.47)^2 + (0.62)^2 - 2(0.47 * 0.62)cosC
0.61 = 0.22 + 0.38 - 0.58 cosC
0.61 - ( 0.22 + 0.38) = - 0.58 cosC
0.01 = - 0.58 cosC
C = cos-1(0.01/-0.58)
C = 91 degrees
Using the sine rule;
b/Sin B = c/Sin C
0.62/sinB = 0.78/sin 91
0.62/Sin B = 0.78
B = sin-1 (0.62//0.78)
B = 53 degrees
Angle A is obtained from the sum of angles in a triangle;
180 - (91 + 53)
A = 36 degrees
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how much force is required to accelerate an 8.6kg wagon by 15 m/s ?
The amount of force required to accelerate the given mass of the wagon is 129 Newtons.
What is force?A force is simply referred to as either a push or pull of an object resulting from the object's interaction with another object.
From Newton's Second Law, force is expressed as;
F = m × a
Where is mass of object and a is the acceleration.
Given the data in the question;
Mass of the rock m = 8.6kgAcceleration a = 15m/s²Force F = ?F = 8.6kg × 15m/s²
F = 129kgm/s²
F = 129N
Therefore the amount of force required to accelerate the given mass of the wagon is 129 Newtons.
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As elements gain more electrons in their outer shells, their electrical
conductivity generally decreases. Which of the following explains this
phenomenon?
Electrical conductivity often decreases, when elements receive additional electrons in their outer shells. As a result of the valence shell being filled, the number of movable electrons decreases.
What is a mobile electron?Electrons are mobile charges in the conduction band while holes are mobile charges in the valence band.
Current flow in a semiconductor is caused by charge carrier migration in both the conduction and valence bands.
Which creates a net motion of positively charged carriers in the same direction as the field and negatively charged carriers in the opposite direction as a result of the force.
The outermost electrons in metals are not bonded to each atom which is shared by many atoms. This decentralization is what allows metals to conduct electric currents.
Hence, the elements gain more electrons in their outer shells, and their electrical conductivity generally decreases.
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Assume that the thickness of the tissue between the interior and the exterior of the body is =3 cm and that the average area through which conduction can occur is =1.5 m2 . Find heat transferred by conduction per hour if temperature difference between the inner body and the skin is ∆ = 2 0C. Coefficient of thermal for tissue without blood is = 18 × 10−2 Cal /m-hr- 0C.
The heat transferred by conduction per hour if temperature difference between the inner body and the skin is ∆ = 2°C is 18 Joule/ hr.
What is heat conduction?Heat conduction is the method of transfer of heat by the direct contact of the two or more solid bodies.
Given is the thickness of tissue x = 3cm =-0.03m, Area of conduction A = 1.5 m², Change in temperature of skin ΔT =2°C, and coefficient of thermal for tissue without blood is k = 18 × 10⁻² Cal /m-hr- °C
The conduction heat rate in hr is
Q =kAΔT /x
Q =18 × 10⁻² x 1.5 x 2 /0.03
Q =18 Joule / hr
Thus, the heat transferred by conduction per hour, if temperature difference between the inner body and the skin is ∆ = 2°C is 18 Joule/ hr.
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Why is digital forensics important?
Hi! digital forensics is important because not only does digital forensics allow cyber security organisations to develop technologies that can prevent hackers from accessing devices, websites and networks but can lead businesses in the direction of understanding exactly what data is compromised.
at what temperature does the fahrenheit scale read quartered the celsius scale ? what is the corresponding reading in kelvin scale ?
The temperature at which the Fahrenheit scale reads quartered the celsius scale is : -5.16 ⁰F, -20.64⁰C
Reading in kelvin scale = 252.5 K
Determine the temperature at which the Fahrenheit scale reads quartered the celsius scaleThe relationship between Fahrenheit and celsius can be expressed as
F = (9/5)(C) + 32 ---- ( 1 )
Therefore the temperature at which Fahrenheit scale quarters the celsius scale is :
F = 1/4 C --- ( 2 )
Back to equation ( 1 )
1/4 C = (9/5)(C) + 32
1/4C - 9/5C = 32
C ( 1/4 - 9/5 ) = 32
C = 32 / ( 1/4 - 9/5 )
= -20.64⁰C
F = 1/4 ( -20.64 ) = -5.16 ⁰F
Hence we can conclude that The temperature at which the Fahrenheit scale reads quartered the celsius scale is : -5.16 ⁰F, -20.64⁰C. Reading in kelvin scale = 252.5 K
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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:
Calculate 9 ∙ 10-5 divided by 3 ∙ 10-9. (Box after the "10" in answer is for the exponent.). ∙ 10 .
The result of 9 ∙ 10-⁵ divided by 3 ∙ 10-⁹ is 3 × 10⁴. Details about exponential functions can be found below.
How to calculate multiplication involving exponentiation?Exponentiation is the process of calculating a power by multiplying together a number of equal factors, where the exponent specifies the number of factors to multiply.
According to this question, the following exponential function is given:
9 × 10-⁵ ÷ 3 × 10-⁹
9/3 × 10-⁵+⁹
3 × 10⁴
Therefore, the result of 9 ∙ 10-⁵ divided by 3 ∙ 10-⁹ is 3 × 10⁴.
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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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which of the following is a key to your success in this pe course
A key to an individual's success in this PE course is honesty.
What is PE?PE is an acronym for physical education and it can be defined as a course (subject) which is taught in schools, so as to provide students with information on how to promote good health and physical fitness.
Some of the factors that affects a student's success in different physical education (PE) courses include the following:
Being in top physical shapeA good memoryGood eyesightHonestyIn this scenario, honesty is key to an individual's success in this PE course.
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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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How much weight can be placed on the spring so that the end of the spring is 2m above the ground?
The weight must be 288N placed on the end of the spring when it is 2m from the ground.
What is gravitational potential energy?If an object is lifted, work is done against gravitational force. The object gains energy.
Given is a spring has a spring constant of 48 N/m. The end of the spring hangs 8 m above the ground. The final height of weight above the ground, h =2m
Using Hooke's law, expressed as
Force, F = k (x₂-x₁).
Put the values, we get
F = 48 (8-2)
F = 288 N
This force applied on the spring is equal to the weight placed on the spring.
Weight W= 288N.
Thus, the weight must be 288N.
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A 5.0 kg box is sitting on a scale in an elevator. Before the elevator moves, the scale reads 49.05 N. When the elevator accelerates into motion, the scale momentarily reads 46.75 N. If the acceleration due to gravity is 9.81 m/s2, what is the magnitude of the acceleration of the elevator? (1 point)
A) 0.46 m/s2
B) 0.57 m/s2
C) 0.87 m/s2
D) 0.91 m/s2
The magnitude of acceleration of the elevator is 0.46m/s². Details on how to calculate magnitude of acceleration can be found below.
How to calculate magnitude of acceleration?The magnitude of acceleration of the accelerator can be calculated by dividing the difference in force by the mass of the accelerator.
According to this question, a 5.0 kg box is sitting on a scale in an elevator. Before the elevator moves, the scale reads 49.05 N, however, when the elevator accelerates into motion, the scale momentarily reads 46.75 N.
Magnitude of acceleration = (49.05 - 46.75)/5
Magnitude of acceleration = 2.3/5
Magnitude of acceleration = 0.46m/s²
Therefore, the magnitude of acceleration of the elevator is 0.46m/s².
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A duck has a mass of 2.70 kg. As the duck paddles, a force of 0.110 N acts on it in a direction due east. In addition, the current of the water exerts a force of 0.220 N in a direction of 47.0° south of east. When these forces begin to act, the velocity of the duck is 0.120 m/s in a direction due east. Find (a) the magnitude and (b) the direction (relative to due east) of the displacement that the duck undergoes in 2.70 s while the forces are acting. (Note that the angle will be negative in the south of east direction.)
a) The magnitude will be 0.838m
b) The displacement will be -17.35°
What is displacement?The path covered by an object from its initial point to final point.
Forces acting on the duck
x-axis: 0.13 + 0.16*cos(-56°) = 2.7 * ax
ax = 0.0813 m/s^2
y-axis: 0.13*sin(-56°) = 2.7 * ay
ay = -0.0491 m/s^2
The displacement on the x-axis
X = Vox * t + ax/2 * t²
X = 0.12* 3.2 + 0.0813/2*3.2²
X = 0.8
The displacement on the y-axis:
Y = Voy * t + ay/2 * t²
X = 0 - 0.0491/2*3.2²
Y=-0.25m
So, the magnitude and angle of this displacement [0.8,-0.25] is:
0.838m at an angle of -17.35°
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Which units are used to measure both velocity and speed? Select three options.
m/s
d/t
km/h
mph
lph
Answer:
m/s
km/h
mph
Explanation:
speed is measured with distance which does in velocity too that is why I chose this answer
The rubber band contains .......potential energy as it is stretched.
less
more
same
Answer:
elastic potential energy
You input potential (stored) energy into the rubber band system when you stretched the rubber band back. Because it is an elastic system, this kind of potential energy is specifically called elastic potential energy.
Explanation:
Which statement describes a chemical property related to the
particles that make up the material?
O
A. Magnesium oxide crystals are hard and brittle because
they are made up of atoms that combine by ionic bonding.
O B. Iron is a good conductor of electricity because the metallic
bonds between its atoms allow electrons to move freely.
O c. Aluminum has a relatively low density because its atoms
have fewer protons than the atoms of most other metals.
O D. Aluminum is relatively inert because its atoms do not react
readily with molecules in the atmosphere.
Iron is a good conductor of electricity because the metallic bonds between its atoms allow electrons to move freely.
What is Chemical property?These are the features which can be observed when the substance undergoes a chemical reaction.
Good conductor of electricity is a chemical property and is common among metals as a result of the metallic bonds which is why option B was chosen.
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