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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1. Identify Give three examples of kinetic energy and three examples of potential energy .
Answer:
Examples of Gravitational Potential Energy
A raised weight.
Water that is behind a dam.
A car that is parked at the top of a hill.
A yoyo before it is released.
River water at the top of a waterfall.
A book on a table before it falls.
A child at the top of a slide.
Ripe fruit before it falls.
Explanation:
Any object in motion is using kinetic energy: a person walking, a thrown baseball, a crumb falling from a table, and a charged particle in an electric field are all examples of kinetic energy at work.
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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ten-story building has identical stairs throughout its stairways. A student calculates the amount of work required to climb one set of stairs and the amount of work to climb the entire ten sets.
Which quantity will remain constant in this experiment?
Answer:
c
Explanation:
Which dog has the most kinetic energy? A. A dog of mass 12 kg running with speed 6 m/s B. A dog of mass 10 kg running with speed 3 m/s C. A dog of mass 16 kg running with speed 5 m/s D. A dog of mass 14 kg running with speed 4 m/s
Answer:
A
Explanation:
KE = 1/2 m v^2
the greatest is A
Calculate the current through the ammeter (look at photo)
Answer:
6 amps
Explanation:by Kirchhoff's loop rule the current at any point in the loop must be equal or charge would be building up. The current at the ammeter is equally to the total current through the sun of the paths in parallel which it is in series with
The power in a circuit is 2 W and the voltage is 20 VDC. What's the circuit current?
Answer:
Power in the circuit is 0.1 amp
Explanation:
The power in the circuit is given by the formula
P = V x I
Where P is Power, V is voltage supplied and I is current in circuit.
so, I = P/v
= 2/20
=0.1 A
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The radius of a nucleus is about 1/10000 that of an atom.
Calculate the radius of a magnesium nucleus.
Give your answer in standard form.
The radius of a magnesium atom is 0.160nm. The radius of a nucleus is about 1/10000 that of an atom.
What is nucleus?The nucleus is an organelle that contains the DNA i.e. genetic material and other materials which is required for cellular processes. It is only found in eukaryotic cells that is responsible for controlling the processes of the cell.
So we can conclude that the radius of a magnesium atom is 0.160nm which is equals to about 1/10000 radius of that atom.
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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.
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:
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Classify each characteristic as either a metal or a nonmetal.
shiny surface
dull surface
good conductor of electricity
good conductor of heat
poor conductor of electricity
poor conductor of heat
malleable
brittle
Answer:
metal, non, metal, metal, non, non, metal, non
Explanation:
knowledge
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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A marble rolls off a tabletop 1.15 m high and hits the floor at a point 4 m away from the tables edge in the
horizontal direction.
a. How long is the marble in the air?
b. What is the speed of the marble when it leaves the tables edge?
Im/s
C. What is its speed when it hits the floor?
A marble rolls off a tabletop 1.15 m high and hits the floor at a point 4 m away from the edge of the table in the horizontal direction,
t= 0.45 seconds.V=2.22m/sVT=4.95 m/sThis is further explained below.
What is its speed when it hits the floor...?Generally, the equation for motion is mathematically given as
S= ut + 0.5at²
Therefore
y = Voy t + 0.5gt^2
1 = 0.5x 98 x 6²
1=4.9t^2
[tex]t=\sqrt{0.2041 }[/tex]
t= 0.45 seconds.
b) Horizontal motions are uniform.
V=Horizontal displacement/time
V=1/0.45
V=2.22m/s
C)
Vx: 2.22 m/s At bottom,
Vy² = Voy² + 2as
Vy² = 2x95x1
Vy² = 19.6
Total velocity
[tex]VT=\sqrt{( 2.22 m/)^2+19.6}[/tex]
VT=4.95 m/s
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According to the law of conservation of energy, which changes would INCREASE the total energy of a system?
A. An addition of 400 J of thermal energy and a loss of 550 J of kinetic energy
B. An addition of 200 J of thermal energy and a loss of 550 J of thermal energy
C. An addition of 300 J of GPE and a loss of 450 J of thermal energy
D. An addition of 500 J of kinetic energy and a loss of 450 J of thermal energy
The changes that would increase the total energy of a system is an addition of 500 J of kinetic energy and a loss of 450 J of thermal energy.
What is conservation of energy?The term conservation of energy means that energy can not be created nor destroyed.
In this case, the changes that would increase the total energy of a system is an addition of 500 J of kinetic energy and a loss of 450 J of thermal energy.
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3. Harris is putting in a three-phase Y-Y-
connected transformer bank and the
secondary line-to-line voltage is 208 V.
What's the line-to-neutral voltage?
O A. 120 V
O B. 359 V
C. 69 V
O D. 240 V
120V is the line-to-neutral voltage .
What is Line Voltage ?It is defined as the voltage of a power transmission circuit or distribution circuit up to the point of transformation or utilization.
The secondary line voltage is [tex]V_{L} = 280 V[/tex]
The notation AC indicates that the current is an alternating current.
The given formula is [tex]V_{ph} = \frac{V_{L} }{\sqrt{3} }[/tex]
Substitute 208 V into the formula
[tex]V_{ph} = \frac{V_{L} }{\sqrt{3} } \\\\V_{ph} = \frac{208V}{\sqrt{3} } \\\\= 120 (Approx)[/tex]
So, the line-to-neutral voltage is 120 V.
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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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A car starts from rest and coasts down a hill with a constant acceleration.If it goes 90m in 8s,find the acceleration and velocity after 8s.
How do light waves differ from sound waves?
Answer:
Light waves are electromagnetic waves while sound waves are mechanical waves. :)
A car of mass 500 kg is moving at a speed of 1.2 m/s. A man pushes the car, increasing the speed to 2 m/s. How much work did the man do?
A. 1360 J
B. 360 J
C. 640 J
D. 1000 J
Answer:
Option B - 360 J
Explanation:
One of the formulas used to find out how much work was done is :
E = 0.5×m×v² (where m is the mass and v is the velocity)
Now we substitute values from the question and simplify :
E = 0.5×500×1.2²
E = 250×1.2²
E = 250×1.44
E = 360 J
So our answer is Option B
Hope this helped and have a good day
Microscopes are used to study the structures of rocks. Over time, microscopes have become more and more powerful.
As a result of this technological improvement, our structural information of rocks
As a result this technological improvement, our structural information of rocks has improved greatly.
What is a petrographic microscope?A petrographic microscope is a type of optical microscope that is used to identify rocks and minerals in very thin sections and also to investigate microscopic textures and features that are present in minerals and rocks.
This has improved greatly recent structural information about rocks.
Hence, microscopes used in the study of structures of rocks has overtime improved greatly our structural information about them
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Answer:
B is the correct answer.
Explanation:
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