Two statements describe reasons a solar cell must contain semiconductors :
A. Semiconductors form a path for the electrons that are released by the photoelectric effect.
C. Semiconductors serve as a source of electrons to form an electrical current.
What is Photoelectric effect?Photoelectric effect, phenomenon in which electrically charged particles are released from or within a material when it absorbs electromagnetic radiation.
When the semiconductor is exposed to light, it absorbs energy and transfers it to the material, due to which energy reaches to negatively charged particle (electron), which allows the electron to flow in the material as electric current .
hence , correct option will be :
A. Semiconductors form a path for the electrons that are released by the photoelectric effect.
C. Semiconductors serve as a source of electrons to form an electrical current.
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what are some hack that I can use to heal up my eyes?
Answer:
All 7 Dragonballs
Explanation:
the dragonball Summon shenron which will then grant you a wish
Olivia and Caitlyn want to know whether the wind affects how far a football will travel. They have one student go outside to the football field when it is not windy and throw the football 30 times. They measure how far the ball goes using a meter stick. On a windy day, they have the same student go to the football field and throw the football 30 times. Again, they measure how far the ball goes using the same meter stick. What is the Independent Variable?
Answer:
presence or absence of wind
Explanation:
When establishing a relationship between two variables the effect one variable has on the other is studied. The variable that changes with respect to the other is the dependent variable while the other variable is called the independent variable.
Here the distance the football covers in the presence and absence of wind is studied. So, the presence or absence of wind is the independent variable.
A planned high-speed train between Houston and Dallas will travel a distance of 386 kilometers in 5.40 × 10^3 seconds. What is the average speed of this train?
¡Hellow!
For this problem, first, lets convert the seconds in hours:
5,4x10³[tex]\rightarrow[/tex] 5400
h = sec / 3600
h = 5400 s / 3600
h = 1,5
Let's recabe information:
d (Distance) = 386 km
t (Time) = 1,5 h
v (Velocity) = ?
For calculate velocity, let's applicate formula:
[tex]\boxed{\boxed{\textbf{d = v * t} } }[/tex]
Reeplace according we information:
386 km = v * 1,5 h
v = 386 km / 1,5 h
v = 257,33 km/h
The velocity of the train is of 257,33 kilometers for hour.
Extra:
For convert km/h to m/s, we divide the velocity of km/h for 3,6:
m/s = km/h / 3,6
Let's reeplace:
m/s = 257,33 km/h / 3,6
m/s = 71,48
¿Good Luck?
Write a short story where the main character needs protection from two different EM radiations
10- The voltage across the generator of
the circuit of figure 13 is 12V and
the voltmeter V2 indicates 8V:
А
ס
N.
V
L1
L2
B
L
Fig.13
a- What would the voltmeter V3 indicate?
Justify the answer
b- What would the voltmeter Vi indicate?
Justify the answer
hey! i just wanted to ask if you found the answer because i’m looking for it
An airplane lands with an initial velocity of 60 m/s and then slows down at 1.5 m/s2 for 30 seconds. What is its final velocity?
a. 3 m/s
b. 15 m/s
c. 98 m/s
d. 105 m/s
A toyota prius can go from 0 m/s to 30 m/s in 15 s. What is its acceleration? Select one: O 15 m/s2 O 2 m/s2 450 m/s2 30 m/s2
Answer:
I think it is 2m/s2
Explanation:
Have a great day:)
someone help me with this please
Answer: are u single
Explanation:
Q. If space is vaccumed then how moon is attracted to earth by it gravity?
Answer:
The vacuum of outer space is not caused by the expansion of the universe, but is caused by gravity.
Explanation:
Gizmo seasons why do we have them answer key
What's the time it takes a car to attain the speed of 30 m/s when accelerating from rest at 2 m/s (squared)
A- 15 s
B- 2 s
C- 60 s
D- 30 s
E- none
Three identical 6.4kg masses are hung by three identical springs. Each spring has a force constant of 7.8 Kn/m and is 12cm long before any masses are attached to it. how long is the bottom most spring going to be after the three masses are hung on it
a. 14.3 b. 16.2 c.12.8 d.10.7
Answer:
The correct option is;
c. 12.8 cm
Explanation:
The given parameters are;
The length of each spring = 12 m = 0.12 m
Given that the masses and the springs are vertically oriented, we have;
The mass on the first spring = 3 × 6.4 = 19.2 kg
The weight on the first spring = 19.2 kg × 9.81 m/s² = 188.352 N
The extension of the first spring = 188.352 N/7,800 N/m ≈ 0.02415 m
The mass on the second spring = 2 × 6.4 = 12.8 kg
The weight on the second spring = 12.8 kg × 9.81 m/s² = 125.568 N
The extension of the second spring = 125.568 N/7,800 N/m ≈ 0.016098 m
The mass on the third spring = 1 × 6.4 = 6.4 kg
The weight on the third spring = 6.4 kg × 9.81 m/s² = 62.784 N
The extension of the third (bottom) spring = 62.784 N/7,800 N/m ≈ 0.00805 m
The total length of the bottom spring = Original length of the bottom spring + Extension of the bottom spring
The total length of the bottom spring ≈ 0.12 m + 0.00805 m = 0.12805 m
The total length of the bottom spring ≈ 0.12805 m ≈ 12.81 cm
The bottom spring will be approximately 12.81 cm long.
The heat loss from a boiler is to be held at a maximum of 900Btu/h ft2 of wall area. What thickness of asbestos (k= 0.10 Btu/h ft ℉) is required if the inner and outer surfaces of the insulation are to be 1600 and 500℉, respectively? Now if a 3-in.-thick layer of kaolin brick (k= 0.07 Btu/h ft ℉) is added to the outside of the asbestos, what heat flux will be result if the outside surface of the kaolin is 250℉? What will be the temperature at the interface between the asbestos and kaolin for this condition?
Answer:
a. 0.122 ft b. -70 Btu/h ft² c. 633.33 °F
Explanation:
a. Since the rate of heat loss dQ/dt = kAΔT/d where k = thermal conductivity, A = area, ΔT = temperature gradient and d = thickness of insulation.
Now [dQ/dt]/A = kΔT/d
Given that [dQ/dt]/A = rate of heat loss per unit area = -900Btu/h ft², k = 0.10 Btu/h ft ℉(for asbestos), ΔT = T₂ - T₁ = 500 °F - 1600 °F = -1100 °F. We need to find the thickness of asbestos, d. So,
d = kΔT/[dQ/dt]/A
d = 0.10 Btu/h ft ℉ × -1100 °F/-900Btu/h ft²
d = 0.122 ft
b. If the 3 in thick Kaolin is added to the outside of the asbestos, and the outside temperature of the asbestos is 250℉, the heat loss due to the Kaolin is thus
[dQ/dt]/A = k'ΔT'/d'
k' = 0.07 Btu/h ft ℉(for Kaolin), ΔT' = T₂ - T₁ = 250 °F - 500 °F = -250 °F and d' = 3 in = 3/12 ft = 0.25 ft
[dQ/dt]/A = 0.07 Btu/h ft ℉ × -250 °F/0.25 ft
[dQ/dt]/A = -70 Btu/h ft²
c. To find the temperature at the interface, the total heat flux equals the individual heat loss from the asbestos and kaolin. So
[dQ/dt]/A = k(T₂ - T₁)/d + k'(T₃ - T₂)/d' where [dQ/dt]/A = -900Btu/h ft², k = 0.10 Btu/h ft ℉(for asbestos), k' = 0.07 Btu/h ft ℉(for Kaolin), T₁ = 1600 °F, T₂ = unknown and T₃ = 250℉.
Substituting these values into the equation, we have
-900Btu/h ft² = 0.10 Btu/h ft ℉(T₂ - 1600 °F)/0.122 ft + 0.07 Btu/h ft ℉(250℉ - T₂)/0.25 ft
-900Btu/h ft² = 0.82 Btu/h ft ℉(T₂ - 1600 °F) + 0.28Btu/h ft ℉(250℉ - T₂)
-900 °F = 0.82(T₂ - 1600 °F) + 0.28(250℉ - T₂)
-900 °F = 0.82T₂ - 1312°F + 70 °F - 0.28T₂
collecting like terms, we have
-900 °F + 1312°F - 70 °F = 0.82T₂ - 0.28T₂
342 °F = 0.54T₂
Dividing both sides by 0.54, we have
T₂ = 342 °F/0.54
T₂ = 633.33 °F
The thickness of asbestos required is 0.122 ft.
The heat flux will be -70 Btu/h ft²
And the temperature of the interface is 633.33 °F.
(i) the rate of heat loss :
dQ/dt = kAΔT/d
where k = thermal conductivity, A = area, ΔT = temperature gradient, and
d = thickness of insulation.
[dQ/dt]/A = kΔT/d
Given that [dQ/dt]/A = rate of heat loss per unit area = -900Btu/h ft²,
k = 0.10 Btu/h ft ℉,
ΔT = 500 °F - 1600 °F = -1100 °F
We have to find the thickness of asbestos that is d.
d = kΔT/[dQ/dt]/A
d = 0.10 Btu/h ft ℉ × -1100 °F/-900Btu/h ft²
d = 0.122 ft is the thickness required.
(ii) a 3-in thick Kaolin is added to the outside of the asbestos
outside temperature of the asbestos is 250℉,
the heat loss due to the Kaolin is:
[dQ/dt]/A = k'ΔT'/d'
k' = 0.07 Btu/h ft ℉(for Kaolin), ΔT' = T₂ - T₁ = 250 °F - 500 °F = -250 °F and d' = 3 in = 3/12 ft = 0.25 ft
[dQ/dt]/A = 0.07 Btu/h ft ℉ × -250 °F/0.25 ft
[dQ/dt]/A = -70 Btu/h ft²
(iii) temperature at the interface
the total heat flux :
[dQ/dt]/A = k(T₂ - T₁)/d + k'(T₃ - T₂)/d'
where [dQ/dt]/A = -900 Btu/h ft²,
k = 0.10 Btu/h ft ℉ (for asbestos),
k' = 0.07 Btu/h ft ℉ (for Kaolin),
T₁ = 1600 °F and T₃ = 250℉.
-900 = 0.10(T₂ - 1600 °F)/0.122 + 0.07(250℉ - T₂)/0.25
-900 = 0.82(T₂ - 1600 °F) + 0.28(250℉ - T₂)
-900 °F = 0.82(T₂ - 1600 °F) + 0.28(250℉ - T₂)
-900 °F = 0.82T₂ - 1312°F + 70 °F - 0.28T₂
-900 °F + 1312°F - 70 °F = 0.82T₂ - 0.28T₂
342 °F = 0.54T₂
Dividing both sides by 0.54, we have
T₂ = 342 °F/0.54
T₂ = 633.33 °F
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help? :(
A 9,300 kg. a railroad car traveling at a velocity of 15m/s strikes a second boxcar at rest. If the two cars stick together and move off with a velocity of 6m/s, what is the mass of the second car?
Answer:
m2 = 13950 [kg]
Explanation:
To solve this problem we must use the principle of conservation of linear momentum, which is defined as the product of mass by velocity, and can be determined by means of the following expression:
P = m*v
where:
P = lineal momentum [kg*m/s]
m = mass [kg]
v = velocity [m/s]
Now that momentum is conserved, we need to analyze the conditions before the collision and after the collision. In this way we must propose the following equation:
ΣPbefore = ΣPafter
(m1*v1) + (m2*v2) = (m1+m2)*v3
where:
m1 = mass of the railroad car = 9300 [kg]
v1 = velocity of the railroad car before the collision = 15 [m/s]
m2 = mass of the box car [kg]
v2 = velocity of the boxcar before the collision = 0 (the car is at rest)
(m1 + m2) = combined mass of the cars, they stick together after the collision [kg]
v3 = combined velocity of the cars after the collision = 6 [m/s]
(9300*15) + (m2*0) = (m1+m2)*6
139500 = (6*9300) + 6*m2
83700 = 6*m2
m2 = 13950 [kg]
The mass of the second railroad car which was initially at rest is 13950kg.
Given the data in the question;
Mass of railroad car1; [tex]m_1 = 9300kg[/tex]Initial velocity of railroad car1; [tex]u_1 = 15m/s[/tex]Mass of railroad car2; [tex]m_2 = \ ?[/tex]
Since railroad car2 was initially at rest,
Initial velocity of railroad car1; [tex]u_2 = 0[/tex]After the strike, the wo cars stick together and moved
Final velocity of both railroad car1 and 2; [tex]v = 6m/s[/tex]To determine the mass of the second railroad car, we use conservation of linear momentum:
[tex]m_1u_1 + m_2u_2 = (m_1 + m_2 )v[/tex]
We substitute our given values into the equation
[tex](9300kg * 15m/s) + ( m_2 * 0 ) = ( 9300kg + m_2 )6m/s\\\\9300kg * 15m/s = ( 9300kg + m_2 )6m/s\\\\139500kg.m/s = 55800kg.m/s + ( m_2 * 6m/s )\\\\139500kg.m/s - 55800kg.m/s = m_2 * 6m/s\\\\83700kg.m/s = m_2 * 6m/s\\\\m_2 = \frac{83700kg.m/s}{6m/s} \\\\m_2 = 13950kg[/tex]
Therefore, the mass of the second railroad car which was initially at rest is 13950kg.
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Drag the tiles to the correct boxes to complete the pairs.
Match the organisms to the descriptions.
scorpion
starfish
octopus
bird
lacks colored blood
had a soft, unsegmented body
is a vertebrate
lacks antennae
The correct matching of the organisms to their descriptions is given below:
Starfish - lacks colored bloodBird - is a vertebrateOctopus - has a soft, unsegmented bodyScorpion - lacks antennaeWhat is an Organism?Any organic, living system that performs as an independent unit is referred to as an organism. Cells comprise all living things. Multicellular mammals, plants, and fungi are examples of multicellular creatures. Unicellular microorganisms include bacteria and archaea.
All kinds of creatures can have the capacity for procreation, growth and development, maintenance, and to some extent, stimulus-response. Multicellular organisms such as beetles, tetrapods, mushrooms, and vascular plants grow a variety of tissues and organs.
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HELP FAST PLEASE. NEWTON'S LAWS.
Which of the following statements is true?
Solar eclipses are safe to look at without special equipment.
The International Date Line runs through Greenwich, England.
New days begin at 180° longitude.
Earth's orbit is a perfect circle.
Answer:
New days begin at 180° longitude.
Explanation:
What is the legal height the player is allowed to serve from a. Above the waist B. Below the waist C. On the waist D. above the chest
Answer: Option B.
Explanation:
I guess that this refers to the Badminton rules, particularly to the position of the racket (or the head of the racket, where the "head" is the part with the net, that you use to hit the shuttle) when serving.
The head of the racket must be swung from below your waist. So the head of the racket must be below your waist before you do the service (With a part of the head is enough).
Then the correct option is B. Below the waist.
Explain how mass and velocity play a big role in the amount of momentum an object has.
Answer:
Momentum is directly proportional to the object's mass and also its velocity. Thus the greater an object's mass or the greater its velocity, the greater its momentum. Momentum p is a vector having the same direction as the velocity v. The SI unit for momentum is kg · m/s.
Answer:
Momentum is directly proportional to the object's mass and also its velocity. Thus the greater an object's mass or the greater its velocity, the greater its momentum. Momentum p is a vector having the same direction as the velocity v. The SI unit for momentum is kg · m/s.
Explanation:
Please, can any one help
Answer:
a = 1.458 [m/s²]
Explanation:
To be able to solve this type of problems it is always advisable to make a free body diagram with the forces acting on the body.
Attached is an image with the free body diagram and the proposed equations, the explanation of obtaining the equations will be described below.
Let's take the movement to the left as positive, i.e. all forces going to the left have a positive sign.
Let's use Newton's second law, which tells us that the sum of forces on a body is equal to the product of mass by acceleration.
To the left we have the two forces of tension by the cosine of the angle. And to the right the frictional force. The resultant of these forces is equal to the product of the mass (mass of the child plus the mass of the sled), by acceleration.
A rock is dropped off a cliff and strikes the ground with an impact velocity of 20m/s. How high was the cliff?(use a=-10m/s2)
Answer:
20 m
Explanation:
by the formula,
[tex]2aS = V_{f}^{2} - V_{i}^2[/tex]
2 x 10 x S = 20^2 - 0
20S = 400
[tex]S = \frac{400}{20}[/tex]
S = 20 m
+ 9. What force (in units of Newtons) is needed to give a 3.5 m/s" acceleration to a 1200 kg car?
Answer:
4200 Newtons
Explanation:
Force = mass x acceleration
1200 x 3.5 = 4200
which statements describes a chemical property
Answer:
a chemical property can be observed without changing the identity of the substance.
Explanation:
a physical property is a characteristic that can be observed without changing the substance into another substance. The object reacts with acid to form water.
A family drives 881 miles from Houston Texas to Santa Fe New Mexico for vacation how long will it take the family to reach their destination if they travel at a velocity of 55.0 miles per hour northwest?
Answer:
about 16 hours
Explanation:
if driving 55mph for 16 hrs you will travel about 880 miles
It takes 39.7 N to push a crate at a constant speed across flat ground where μk=0.438 what is the mass of the crate
Answer:
I don't know how to show the work but I just had this question and the answer is 9.24kg.
Explanation:
???whats the answers??
The answers is 30 miles per hour, the driver is speeding the car up, section-H, 12 minutes, section-D, and 65 miles per hour.
what is Newton's second law?
F=mXa
a=F/m
m=F/a
All of the above
It should be the first one, F= mXa (F = m times a).
A
1. Runners A, B, and C are running a race. Based on their locations, which 20 points
runner is experiencing acceleration?
Answer:
B) 48 metres
Explanation:
How are the layers of the Earth similar and different from one another?
Answer:
the innermost layer of the earth
Explanation:
the earth has an outer core liquid and an inner core solid they are not chemically distinct from each other but they are chemically distinct from the mantle the core is mainly composed of nickel and iron
True or False: Heavy elements such as Carbon and Nitrogen, that are necessary for life were created in the Big
Bang and have been around in the Universe since that time.
Answer:
i believe the answer is true
Explanation:
everything was created in the big bang