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
The speed of the cart after 3 seconds of Low fan speed is
The speed of the cart after 3 seconds of Low fan speed is (2) cm/s. This is further explained below.
What is speed?Generally, speed is simply defined as the rapidity of movement or efficiency of operation.
In conclusion, After 8 seconds with the fan set at Low, the cart will have traveled 1 cm/s. After three seconds at medium fan speed, the cart travels at a velocity of two centimeters per second.
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A doctor has a patient blow on one side of a U-shaped tube that is partially
filled with water and has a ball floating on the other side, as shown in the
image below. If the ball rises with a force of 200 N, what pressure did the
patient apply to his side of the tube?
Answer: 100,000 Pa
Explanation:
[tex]$$Applied Force $=200 \mathrm{~N}$ \\Area $=0.002 \mathrm{~m}^{2}$\\\\Pressure $=\frac{\text { Force }}{\text { Area }}$\\$=\frac{200}{0.002}$\\$=\frac{200}{2 \times 10^{-3}}$\\$=100,000 \mathrm{~Pa}$[/tex]
a man has a mass of 85kg what is his weight
Answer:
See below
Explanation:
F = ma
= 85 * 9.8 = 833 N
OR this could be written as 187.4 pounds
OR 187 kg-weight (not just kg)
85 kg is a measure of MASS, but is often (though improperly) used as weight on earth.
Does dispersive power of the material of a prism depends upon the shape, size and angle of prism? Explain.
The dispersive power of the material of the prism is independent of the shape, angle of prism or size of the prism. It depends only on the refractive index [tex]{(\mu)}[/tex] of the material of the prism.
Answer:
We can see that the angular dispersion of a prism is dependent on the angle of the prism but dispersive power does not depend on the geometry of the prism.
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
HELP THIS LAST DAY!!!
Answer:
The proton has much greater mass
Explanation:
Protons and electrons are part of an atomProton exists inside nucleus whereas electron keep moving around the nucleusElectrons have negative charge where as protons have positive charge .Answer:
D, a proton has a much greater mass.
Explanation:
An electron has a mass close to nothing.
describe fluid friction and static friction in your own words
Answer:
friction
Explanation: The resistance that one surface or object encounters when moving over another.
The object was thrown vertically upwards at a speed of 30 m / s. How high does the body go?
and how long does it take to get back to the point of shooting?
Answer:
4.9
Explanation:
Velocity half second before maximum height = Velocity half second after maximum height (Return journey)
For downward journey :
Initial velocity u=0 m/s
We have g=9.8 m/s
Time t= ½s
s
Thus velocity after half second v=u+gt
v=0+9.8× ½ =4.9m/s
edward travels 150 kilometers due west and then 200 kilometers in a direction 60 degrees north of west.what is his displacement in the westerly direction?
The displacement of Edward in the westerly direction is determined as 338.32 km.
What is displacement of Edward?The displacement of Edward can be determined from different methods of vector addition. The method applied here is triangular method.
The angle between the 200 km north west and 150 km west = 60 + 90 = 150⁰
The displacement is the side of the triangle facing 150⁰ = R
R² = a² + b² - 2abcosR
R² = 150² + 200² - (2x 150 x 200)xcos(150)
R² = 62,500 - (-51,961.52)
R² = 114,461.52
R = 338.32 km
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If you apply an effort of 240N to a simple machine with a mechanical advantage of 3, what resistance force will the machine produce?
Answer:
720
Explanation:
240x3=720
calculate the momentum, A bald eagle with a mass of 26.4 kg and velocity of 15.6 m/s
Answer:
411.84 kg m/s
Explanation:
Formula :
Momentum = mass × velocity
=========================================================
Given :
⇒ mass = 26.4 kg
⇒ velocity = 15.6 m/s
=========================================================
Solving :
⇒ Momentum = 26.4 × 15.6
⇒ Momentum = 411.84 kg m/s
Ethanol has a specific latent heat of evaporation of 855kJ/kg. Calculate
the energy required to boil 0.60kg of ethanol.
From the calculation , we can see that the specific heat capacity is 513 kJ
What is the specific heat capacity?The specific heat capacity is the heat that can be able to raise the temperature of 1 Kg of a material by 1K.
Now;
We know that;
Latent heat of evaporation = 855kJ/kg
Mass of the liquid = 0.60kg
H = mL
H = 0.60kg * 855kJ/kg
H = 513 kJ
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Explain how the intensity of the UV light varies across the Earth
Answer:
Much more UV radiation is absorbed and less reaches the Earth. UV levels are higher closer to the equator. Closer to the equator the sun's rays have a shorter distance to travel through the atmosphere and therefore less of the harmful UV radiation can be absorbed.
Explanation: Hope it helps you :)))))
Have a good day
Scientists can help us understand the impact of human activities on the environment. True or false?
Answer:
True
Explanation:
hope it will help you
help which is the balanced equation
Answer:
b
Explanation:
Mechanical energy is the sum of
energy and potential energy.
Answer:
True, the total amount of mechanical energy is merely the sum of the potential energy and the kinetic energy. This sum is simply referred to as the total mechanical energy.
Explanation: Hope it helps you:))))
have a good day
the process by of cell division in which one parent cell produces two identical daughter cells is
Answer:
Mitosis
Explanation:
Mitosis is a process of nuclear division in eukaryotic cells that occurs when a parent cell divides to produce two identical daughter cells. During cell division, mitosis refers specifically to the separation of the duplicated genetic material carried in the nucleus.
Which statement accurately describes how voltage and electrical power are related?
Voltage is always twice the amount of power. This is statement is accurately describe the relationship between voltage and electric power.
What is Power?
Power is defined as amount of energy transferred or converted per unit time.
From power-current relation
P=VI
Also, From Ohm's Law we know that,
V= IR
Replacing the value of V in the above equation,
[tex]P =\frac{I^{2} }{R}[/tex]
When the values for current and resistance are given then the equation is,
[tex]P =\frac{V^{2} }{R}[/tex]
Hence , Voltage is twice to the electric Power.
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One problem with digital data is that it can be vulnerable to hackers.
What is a hacker?
O A. A program that changes analog data into stored digital data
O B. A person who modifies stored digital data so that it is
copied perfectly
O c. A person who gains unauthorized access to digital data
O D. A program that protects stored digital data from computer
viruses
One problem with digital data is that it can be vulnerable to hackers. A Hacker is a person who gains unauthorized access to digital data. Thus, Option C is the correct answer.
What is a Hacker?The word Hacker usually refers to a person who will uses computer to access individually to overcome the technical issues. Not only technical problem some person also use the computer to involve in the unauthorized data for the process of criminal behaviors.
They will make the data or information to get deleted and also steal or change the data in an unauthorized way.
Thus, if there was a problem with digital data is that it can be vulnerable then a person who gains unauthorized access to digital data is known as Hacker.
So, Option C is the correct answer.
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Answer:
O C. A person who gains unauthorized access to digital data
Explanation:
8. Ella wants to replace old bulbs of her home with new LED bulbs. She buys LED bulb that has inbuilt AC to DC converter of output 5V and 2.5A. a. If the LED is 75% efficient, what would be the power dissipated? b. Find the work done by the LED when it is connected to the power supply and left for 1hour 15 minutes.
The power dissipated by the LED is 20 Watts and the work done for 1 hour 15 minutes is 56.25 kJ.
What is electrical power?Electrical power is the rate at which electrical work is done.
Electrical power = voltage × currentThe LED is 75% efficient means that 75% of power dissipated by the LED is converted to light.
Total power dissipated = 5 × 2.5 = 12.5 Watts
Work done = power × time (in seconds)Work done = 12.5 × (1 × 3600 + 15 × 60)
Work done = 56250 J = 56.25 kJ
Therefore, the power dissipated by the LED is 20 Watts and the work done for 1 hour 15 minutes is 56.25 kJ.
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At what height from the surface of earth will the value of 'g' reduced to 64% from the value at the surface? Radius of earth = 6400 Km
Answer: 1600 km from the surface
Explanation:
[tex]E = \frac{GM}{R^{2} }\\g1 = \frac{GM}{R1^{2} } \\R1 = 6400 km\\g2 = 0.64g1\\\frac{g1}{g2} = \frac{\frac{GM}{R1^{2} } }{\frac{GM}{R2^{2} } } \\\frac{g1}{0.64g1} = \frac{R2^{2}}{R1^{2} }\\\frac{1}{0.64} = \frac{R2^{2}}{6400^{2} }\\\\\frac{1}{0.8} = \frac{R2}{6400}\\\\R2 = \frac{6400}{0.8}\\R2 = 8000 km\\[/tex]
Therefore, 8000 km - 6400 km = 1600 km from the surface
This country and the chairs they experience after their independence was , in part due to lack of experience in democratic self -government
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Congo/Zaire region is the country which experienced chaos after their independence due to lack of experience in democratic self-government.
What is Democracy?
This type of government involves the people making legislative decisions and choosing those who will rule and represent them.
Congo/Zaire region was not self sufficient and were inexperienced in democratic self-government after independence which led to political crisis.
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Why we need to remove seeds from cotton balls?
Answer:
Hope this helps!
Explanation:
The seeds are removed for two reasons:
- You cannot spin cotton into a yarn if there are seeds still in the cotton.
- The seeds are a very valuable component of cotton and have a variety of uses.
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
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.
A boy spins a top on a table. How can he INCREASE the total energy of this system?
A. Decrease the height of the table
B. Spin the top more slowly
C. Spin the top faster
D. Increase the friction of the table.
He can increase the total energy of the system by spinning the top faster.
What is energy?The term energy refers to the ability to do work. The total energy of the system refers to the gravitational potential energy and the rotational energy of the top.
Hence, he can increase the total energy of the system by spinning the top faster.
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You observe your friend standing in line at the cafeteria. You conclude they are buying lunch today. This is an example of: A. A scientific theory. B. An independent variable. C. An inference. D. A hypothesis
Answer:
5875yuguggjgefutfhyds
Explanation:
hfgjffiig
Which statement best describes the relationship between atoms and nuclear forces? (2 points)
Group of answer choices
Strong nuclear forces hold the nucleus of an atom together. Weak nuclear forces hold neutrons and electrons together.
Weak nuclear forces hold the nucleus of an atom together. Strong nuclear forces are responsible for breaking down atoms.
Weak nuclear forces hold small atoms together. Strong nuclear forces hold large atoms together.
Strong nuclear forces hold the nucleus of an atom together. Weak nuclear forces are involved when certain types of atoms break down.
Answer:
D. Strong nuclear forces hold the nucleus of an atom together. Weak nuclear forces are involved when certain types of atoms break down.
Explanation:
The diagram above shows a metal disk of weight 1.0 N resting on an index card that is balanced on top of a glass. What is the normal force acting on the metal disk?
If the weight of the metal disk is 1.0 N, the normal force acting on the metal disk is also 1.0 N but acting in the opposite direction.
What is the normal force?According to Newton Law, action and reaction are equal and opposite. The reaction force is equal in magnitude to the weight of an object but opposite in direction.
Having said that, if the weight of the metal disk is 1.0 N, the normal force acting on the metal disk is also 1.0 N but acting in the opposite direction.
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