Answer:
(a) [tex]\frac{P_{250k}}{P_{2000k}}=2.4\ x\ 10^{-4}[/tex]
(b) P = 0.816 Watt
Explanation:
(a)
The power radiated from a black body is given by Stefan Boltzman Law:
[tex]P = \sigma AT^4[/tex]
where,
P = Energy Radiated per Second = ?
σ = stefan boltzman constant = 5.67 x 10⁻⁸ W/m².K⁴
T = Absolute Temperature
So the ratio of power at 250 K to the power at 2000 K is given as:
[tex]\frac{P_{250k}}{P_{2000k}}=\frac{\sigma A(250)^4}{\sigma A(2000)^4}\\\\\frac{P_{250k}}{P_{2000k}}=2.4\ x\ 10^{-4}[/tex]
(b)
Now, for 90% radiator blackbody at 2000 K:
[tex]P = (0.9)(5.67\ x\ 10^{-8}\ W/m^2.K^4)(1\ x\ 10^{-6}\ m^2)(2000\ K)^4[/tex]
P = 0.816 Watt
What is average speed???
Answer:
total distance dibide by total time
A small block is attached to a spring with a spring constant of 85 N/m. When the spring is compressed 0.30 meters and the released, the 0.50 kg block is launched. What is the final speed of the block?
A)
8.42 m/s
B)
3.91 m/s
C)
7.14 m/s
D)
15.3 m/s
Answer:
Explanation:
These Hooke's Law problems are tricky. Here's what we need to know that clears up the problem entirely. The final and also the max speed of the block will be reached at the point where the potential energy of the system is 0. So the equation we need, namely,
[tex]KE+PE=\frac{1}{2}kA^2[/tex] can be simplified down to
[tex]KE=\frac{1}{2}kA^2[/tex] and we solve this first for KE:
[tex]KE=\frac{1}{2}(85)(.30)^2[/tex] and, paying NO attention whatsoever to significant digits here (because if you did the answer you get is not one of the choices)
KE = 3.825 J. Now we can use that value of kinetic energy and solve for the speed we need:
[tex]KE=\frac{1}{2}mv^2[/tex] so
[tex]3.825=\frac{1}{2}(.50)v^2[/tex] so
[tex]v=\sqrt{\frac{2(3.825)}{.50} }[/tex] so
v = 3.91 m/s
1) the wavelengths property that makes it possible for sound to be heard around a bend is A) diffraction. B) Reflection C) refraction. D) interference
2) which property of sounds do bats use to detect their paths?
A) Diffraction B) reflection C) Refraction D) interference
please give a reason or an explanation for each answer you choose
Answer:
1. A
2. B
Explanation:
Sound are mechanical waves that are highly dependent on matter for their propagation and transmission.
Sound travels faster through solids than it does through either liquids or gases.
Wavelength can be defined as the distance from one peak to the next peak of a waveform. This distance is also equal to the distance from one trough of a wave to another.
Diffraction is a wavelength property that makes it possible for sound to be heard around a bend. Thus, it's a property that causes a change in the direction of a wave as it travels through or around a barrier (obstacle) in its path.
Simply stated, diffraction involves the bending of waves around small obstacles with their dimensions smaller than or approximately equal to the wavelength of the sound wave.
On the other hand, reflection can be defined as a phenomenon which typically involves a change in the direction of a wave (bounces back) as it falls on a surface.
Hence, reflection is the property of sounds which animals such as bats use to detect their paths as they navigate from one point to another. This phenomenon is generally referred to as echolocation and it typically involves the use of reflection (echo) of sound to gain information about the nature and location of surrounding objects.
Aiden is writing a report about the structure of the atom. In her report, she says that the atom has three main parts and two subatomic particles. Do you agree with her? Why or why not?
Answer:
I don't agree
Explanation:
Atoms have 3 subatomic particles protons, electrons and neutrons,
The school bag of four students A,B,C,D measures 9kg, 2800gm, 2kg and 8000gm respectively. Whose bag is the lightest
Answer:
Student C
Explanation:
order from heaviest to lightest is...
9 kg (A) , 8000g (8 kg) (D) , 2800g (2.8kg) (B), 2 kg (C)
dimension of radius of sphere
Answer:
The dimension is L
Explanation:
Dimension analysis is a method of representing quantities majorly with respect to some fundamental quantities of mass (M), length (L), time (T).
A sphere has a definite volume which relates to its radius by:
V = [tex]\frac{4}{3}[/tex][tex]\pi[/tex][tex]r^{3}[/tex]
In this equation [tex]\pi[/tex] is a dimensionless quantity, and the unit of v is [tex]m^{3}[/tex].
But, metre is a measure of length, thus it has a dimension of L.
So that,
[tex]m^{3}[/tex] ≅ [tex]L^{3}[/tex]
Then,
[tex]L^{3}[/tex] = [tex]r^{3}[/tex]
Find the cube root of both sides to have,
r = L
Therefore, the dimension of the radius of a sphere is L.
.If a vehicle covers 3 km in 5 minutes, calculate the speed of the vehicle? (With process )
Answer:
Speed = 1.6 m/s
Explanation:
Formula,
Speed = Distance ÷ Time
Rewrite the false statements correctly
1.If an object sinks in one liquid and floats on another liquid,it implies that the density of second liquid is less than the first liquid.
2.The immersed volume of body in a liquid depends on density of the liquid.
3.Relative density of a body is usually expressed in kgm^-3
Explanation:
1. if an object sjnks in one liquid and floats on another liquid it implies that the density of second liquid is greater than the density of first liquid
a cell of EMF 1.5 volt is connected in series with a resistor of Resistance 3 ohms a high resistance voltmeter connected across the cell registers 0.9 volt calculate the internal resistance of the cell
Answer:
0.6 resistance
Two parallel circular rings of radius R have their centres in the X axis separated by a distance L. If each ring carries a uniformly distributed charge Q,find the electric field at points along the X axis
Answer:
E" = Q/4πε₀√[(x² + R²)]³(x - (L - x)/√[(L - 2x)L/(x² + R²) + 1]³})
Explanation:
The electric field due to a charged ring of radius R at a distance x from the center of the ring when the axis of the ring is located on the x - axis is
E = Qx/4πε₀[√(x² + R²)]³
Since the rings are separated by a distance L, the electric field at point x due to the second ring is E' = -Q(L - x)/4πε₀[√((L - x)² + R²)]³. It is negative since it points in the negative x - direction.
So, the resultant electric field at x is E" = E + E' = Qx/4πε₀[√(x² + R²)]³ + {-Q(L - x)/4πε₀[√((L - x)² + R²)]³}
E" = Qx/4πε₀√[(x² + R²)]³ - Q(L - x)/4πε₀√[((L - x)² + R²)]³
E" = Q/4πε₀(x/√[(x² + R²)]³ - (L - x)/√[((L - x)² + R²)]³})
E" = Q/4πε₀(x/√[(x² + R²)]³ - (L - x)/√[(L² - 2Lx + x² + R²)]³})
E" = Q/4πε₀(x/√[(x² + R²)]³ - (L - x)/√[(L - 2x)L + (x² + R²)]³})
E" = Q/4πε₀√[(x² + R²)]³(x - (L - x)/√[(L - 2x)L/(x² + R²) + 1]³})
So, the electric field at points along the x axis is
E" = Q/4πε₀√[(x² + R²)]³(x - {(L - x)/√[(L - 2x)L/(x² + R²) + 1]³})
Q7 Explain how light can be reflected at lots of different angles from a rough surface and still obey the law of reflection. Use a diagram in your answer.
Q8 Read the following statements.
A: You can have refraction without dispersion
B: You cannot have dispersion without refraction
a Discuss a situation where statement A is true.
b Discuss a situation where statement B is true.
Q9 A light year is the distance that light travels in a year. It takes light about 8.3 minutes (or 500 seconds) to travel the 150 million km from the Sun. a Calculate how far light travels in 1 second.
b The Moon is 1.3 light seconds from Earth. Calculate how far away it is in km.
Explanation:
Q7Answer=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 .
list 8 countries which have launched satellites into space and also list the name of the satellite which was launched by the countries
trong chân không có 2 điện tích điểm q1=3.10^-6C và q2=-6.10^-6C đặt tại A và B tương ứng cách nhau 100cm. Tính lực điện thành phần và tổng hợp do q1, q2 tác dụng lên q0=5.10^-6C đặt tại M
Answer:
ya bestie Anda benar terima kasih nanti sekarang selamat tinggal
When you flip a penny (2.35 g), it leaves your hand and moves upward at 2.85 m/s. Use energy to find how high the penny goes above your hand before stopping. A (b) The penny then falls to the floor, 1.26 m below your hand. Use energy to find its speed just before it hits the floor. A (c) Explain your choice of reference level for parts (a) and (b). C (d) Choose a different reference level and repeat part (b)
Answer:
a. 0.41 m
b. 5.72 m/s
c. i. For part (a), I chose the hand as the reference level since the penny was thrown from the hand and the height of the penny at the hand is zero and also, it is easier to calculate from a zero reference level.
ii. For part (b), I chose the ground as the reference level since the height of the penny above the ground is positive and the height of the penny when the penny hits the ground is zero and also, it is easier to calculate from a zero reference level.
d. 5.72 m/s
Explanation:
a. Use energy to find how high the penny goes above your hand before stopping.
Taking the hand as the ground level, and from the law of conservation of energy, the total mechanical energy at the hand, E equals the total mechanical energy when the penny stops in the air, E'.
E = E'
U + K = U' + K' where U = initial potential energy at hand level = mgh where h = height at hand level = 0, K = initial kinetic energy at hand level = 1/2mv² where v = speed at hand level = 2.85 m/s, U' = final potential energy at stopping level = mgh' where h' = height at stopping level, K = final kinetic energy at stopping level = 1/2mv'² where v = speed at stopping level = 0 m/s (since the penny momentarily stops)
So, U + K = U' + K'
mgh + 1/2mv² = mgh' + 1/2mv'²
substituting the values of the variables into the equation, we have
mg(0) + 1/2m(2.85 m/s)² = mgh' + 1/2m(0 m/s)²
0 + 1/2m(8.1225 m²/s²) = mgh' + 0
m(4.06125 m²/s²) = mgh'
h' = 4.06125 m²/s² ÷ g
h' = 4.06125 m²/s² ÷ 9.8 m/s²
h' = 0.41 m
(b) The penny then falls to the floor, 1.26 m below your hand. Use energy to find its speed just before it hits the floor.
Taking the hand as the ground level, and from the law of conservation of energy, the total mechanical energy when the penny stops in the air, E' equals the total mechanical energy on the ground, E"
E' = E"
U' + K' = U" + K" where U' = initial potential energy at stopping level = mgh" where h' = height at stopping level = height of penny above hand, h' + height of hand above ground = 0.41 m + 1.26 m = 1.67 m, K = initial kinetic energy at stopping level = 1/2mv'² where v = speed at stopping level = 0 m/s (since the penny momentarily stops), U = final potential energy at ground level = mgh₁ where h₁ = height at ground level = 0, K = final kinetic energy at ground level = 1/2mv"² where v" = speed at ground level,
So, U' + K' = U' + K'
mgh" + 1/2mv'² = mgh₁ + 1/2mv"²
substituting the values of the variables into the equation, we have
mg(1.67 m) + 1/2m(0 m/s)² = mg(0) + 1/2mv"²
1.67mg + 0 = 0 + 1/2mv"²
1.67mg = 1/2mv"²
1.67g = 1/2v"²
v"² = 2(1.67g)
v" = √[2(1.67g)]
v" = √[2(1.67 m × 9.8 m/s²)]
v" = √[2(16.366 m²/s²)]
v" = √[32.732 m²/s²)]
v" = 5.72 m/s
(c) Explain your choice of reference level for parts (a) and (b).
i. For part (a), I chose the hand as the reference level since the penny was thrown from the hand and the height of the penny at the hand is zero and also, it is easier to calculate from a zero reference level.
ii. For part (b), I chose the ground as the reference level since the height of the penny above the ground is positive and the height of the penny when the penny hits the ground is zero and also, it is easier to calculate from a zero reference level.
(d) Choose a different reference level and repeat part (b)
Taking the hand as the ground level, and from the law of conservation of energy, the total mechanical energy when the penny stops in the air, E' equals the total mechanical energy on the ground, E"
E' = E"
U' + K' = U" + K" where U' = initial potential energy at stopping level = mgh' where h' = height at stopping level = 0.41 m, K = initial kinetic energy at stopping level = 1/2mv'² where v' = speed at stopping level = 0 m/s (since the penny momentarily stops), U = final potential energy at ground level = mgh₁ where h₂ = height of hand above the ground level = height of ground below hand = -1.26 m(it is negative since the ground is below the hand), K = final kinetic energy at ground level = 1/2mv"² where v = speed at ground level,
So, U' + K' = U' + K'
mgh' + 1/2mv'² = mgh₂ + 1/2mv"²
substituting the values of the variables into the equation, we have
mg(0.41 m) + 1/2m(0 m/s)² = mg(-1.26 m) + 1/2mv"²
0.41mg + 0 = -1.26 mg + 1/2mv"²
0.41mg + 1.26mg = 1/2mv"²
1.67mg = 1/2mv"²
1.67g = 1/2v"²
v"² = 2(1.67g)
v" = √[2(1.67g)]
v" = √[2(1.67 m × 9.8 m/s²)]
v" = √[2(16.366 m²/s²)]
v" = √[32.732 m²/s²)]
v" = 5.72 m/s
A balloon blown up with air hanging in a room. as the air in the room becomes colder the balloon becomes smaller because the molecules of air become?
Susan claims that she can throw a dart at a dartboard from a distance of 3.0m and hit the 5.0cm wide bull's-eye if she throws horizontally with a speed of 20 m/s. She starts to throw at the same height as the top of the bull's-eye. Will Susan hit the bull's-eye?
What is being asked? How to calculate?
The momentum of an object is 2.5 kg•m/s, and it is travelling at a speed of 100 m/s.
a) What is the mass of the object?
Answer:
Refer to the attachment!~
Rewrite the false statements correctly
1.A hydrometer sinks less in a lighter liquid
2.The upthrust is equal to the weight of the liquid displaced by the body
Explanation:
A hydrometer sinks more in a lighter liquid
what are the 3 formulas which describe the relationship between mass force and acceleration
Explanation:
Newton's second law of motion gives the relation between mass, force and acceleration.
We know that,
Force, F = mass (m) × acceleration (a)
or
[tex]m=\dfrac{F}{a}[/tex]
or
[tex]a=\dfrac{F}{m}[/tex]
Hence, this is the required solution.
.Una moto circula a 72km/h. Frena hasta detenerse y tarda 10 segundos en dicha operación.
Calcula su aceleración. Calcula la distancia que recorrió hasta detenerse.
Answer:
I. Aceleración, a = -2 m/s²
II. Distancia, S = 100 metros
Explanation:
Dados los siguientes datos;
Velocidad inicial = 72 km / h
Tiempo = 10 segundos
Velocidad final = 0 m/s
Conversión:
72 km/h a metros por segundo = 72 * 1000/3600 = 72000/3600 = 20 m/s
I. Para encontrar la aceleración, usaríamos la primera ecuación de movimiento;
[tex] V = U + at[/tex]
Dónde;
V es la velocidad final. U es la velocidad inicial. a es la aceleración. t es el tiempo medido en segundos.Sustituyendo en la fórmula, tenemos;
[tex] 0 = 20 + a*10 [/tex]
[tex] -20 = 10a [/tex]
[tex] Aceleracion = \frac{-20}{10}[/tex]
Aceleración, a = -2 m/s²
Nota: el signo negativo indica desaceleración o retraso.
II. To find the acceleration, we would use the third equation of motion;
[tex] V^{2} = U^{2} + 2aS [/tex]
Dónde;
V es la velocidad final. U es la velocidad inicial. a es la aceleración. S es la distancia.Sustituyendo en la fórmula, tenemos;
[tex] 0^{2} = 20^{2} + 2*(-2)*S [/tex]
[tex] 0 = 400 - 4S [/tex]
[tex] 4S = 400 [/tex]
[tex] S = \frac {400}{4}[/tex]
Distancia, S = 100 metros
If a receiver is overly selective:
A) the tank circuits within the tuned amplifiers have insufficient Q.
B) too much noise is picked up and amplified by the receiver.
C) only part of the bandwidth of the AM signal is amplified, causing some of the sideband information to be lost and distortion results.
D) the volume control is turned up to maximum, the desired station is very weak.
Answer:
C) only part of the bandwidth of the AM signal is amplified, causing some of the sideband information to be lost and distortion results.
Explanation:
Selectivity is the ability of a receiver to respond only to a specific signal on a wanted frequency and reject other signals nearby in frequency.
If a receiver is overly selective, only part of the bandwidth of the AM signal is amplified, causing some of the sideband information to be lost and distortion results. Whereas, if a receiver is underselective, the receiver can pick different signals on different frequencies at the same time.
a) How much electrical energy, in joules, does a 1000W space heater consume when it runs for 8h? (b) How much energy is that in kilowatt hours? (c) Calculate the cost of using this heater if 1kWh costs 0.5 dollars.
Answer:
a. Energy = 28800000 Joules
b. Energy = 8 Kwh
c. Cost = $4
Explanation:
Given the following data;
Power = 1000 Watts
Time = 8 hours
Cost = $0.5 per KWh
Conversion:
1 hour = 60 * 60 = 3600 seconds
8 hour = 8 * 3600 = 28800 seconds
a. To find much electrical energy, in joules;
Energy = power * time
Energy = 1000 * 28800
Energy = 28800000 Joules
b. To find how much energy is that in kilowatt hours;
Energy = power * time
Energy = 1000 * 8
Energy = 8000 Watt-hour = 8000/1000 = 8 Kwh (1 Kilowatts is equal to 1000 watts).
c. To calculate the cost of using this heater;
Cost = 8 * 0.5
Cost = $4
A train starts from rest and leaves Greenburg station with an acceleration of 1.20 meters per second2. How long does it take the train to travel a distance of 500 meters?
Answer:
Time, t = 28.87 seconds
Explanation:
Given the following data;
Acceleration = 1.20 m/s²
Distance = 500 meters
Initial velocity = 0 m/s
To find the time to cover the distance, we would use the second equation of motion;
[tex] S = ut + \frac {1}{2}at^{2}[/tex]
Where;
S represents the displacement or height measured in meters.
u represents the initial velocity measured in meters per seconds.
t represents the time measured in seconds.
a represents acceleration measured in meters per seconds square.
Substituting into the equation, we have;
[tex] 500 = 0*t + \frac {1}{2}*(1.2)*t^{2}[/tex]
[tex] 500 = 0 + 0.6*t^{2} [/tex]
[tex] 500 = 0.6t^{2} [/tex]
[tex] t^{2} = \frac {500}{0.6} [/tex]
[tex] t^{2} = 833.33 [/tex]
Taking the square root of both sides, we have;
[tex] t = \sqrt{833.33} [/tex]
Time, t = 28.87 seconds
The rhinestones in costume jewelry are glass with index of refraction 1.50. To make them more reflective, they are often coated with a layer of silicon monoxide of index of refraction 2.00. What is the minimum coating thickness needed to ensure that light of wavelength 576 nm and of perpendicular incidence will be reflected from the two surfaces of the coating with fully constructive interference
Answer:
[tex]T=62.9*10^{-9}[/tex]
Explanation:
From the question we are told that:
Index of refraction of Rinestones [tex]\gamma_1 =1.5[/tex]
Index of refraction of silicon [tex]\gamma_2 =2.0[/tex]
Wavelength [tex]\lambda=576nm=576*10^{-9}[/tex]
Let each layer have thickness T
Therefore
Total Thickness =2T
Generally the equation for Constructive interference is mathematically given by
[tex]2T=(m+0.5)\frac{l\lambda}{\gamma_2}[/tex]
Where
[tex]M=0[/tex]
[tex]2T=(0+0.5)\frac{576*10^{-9}}{2*2.0}[/tex]
[tex]T=62.9*10^{-9}[/tex]
If you're walking on the ice cream at 5 ounces per toaster, and your bicycle loses a sock, how much gravy will you need to repaint your hamster?
Answer:
False you dont repaint your hamster.
Explanation:
LOL
What is kinetic and potential energy?
Answer:
the energy produced in a body due to its motion is kinetic energy.
energy produced in a body due to its position is potential energy.
Explanation:
kinetic energy is the energy possessed by a body in motion
Potential energy is the energy possessed by a body by virtue of its position with respect to a reference level
as water begins to boil in the kettle the hotter water at the bottom of the kettle closest to the stove begins to rise and the cooler water a above sinks warms. why does the occur?
Answer:
condensation?
Explanation:
4 kg
4 kg
4 kg
Height =1.6 m
Teacher
Position 2
Height = 1.6 m
Edit
LEI
:
5. Let's say that the teacher raised the lawn bowling ball to a height of 1.6 meters before
they released it. THE LAWN BOWLING BALL HAS A MASS OF 4KG. Remember that
"g" ALWAYS equals 9.8 m/s?. Calculate the gravitational potential energy of the lawn
bowling ball at this position (position 1).
Answer:
E = 62.72 J
Explanation:
Given that,
The mass of a ball, m = 4 kg
The teacher raised the lawn bowling ball to a height of 1.6 meters before they released it.
We need to find the gravitational potential energy of the ball.
We know that,
E = mgh
Where
g is acceleration due to gravity
So,
E = 4 kg × 9.8 m/s² × 1.6 m
E = 62.72 J
So, the gravitational potential energy of the ball is equal to 62.72 J.
A mobile phone is 35% efficient. Over half an hour 11 kJ of energy is transferred to the phone.
Calculate the amount of energy usefully transferred by the machine over half an hour.
[tex]\\ \sf\longmapsto 35\%\:of 11[/tex]
[tex]\\ \sf\longmapsto 35\%\times 11[/tex]
[tex]\\ \sf\longmapsto \dfrac{35}{100}\times 11[/tex]
[tex]\\ \sf\longmapsto \dfrac{385}{100}[/tex]
[tex]\\ \sf\longmapsto 3.85KJ[/tex]
[tex]\\ \sf\longmapsto 3850J[/tex]
Compared to stored analog data, what is a disadvantage of stored digital
data?
A. Multiple copies of the stored data take up very little space.
B. They lose quality when they are copied several times.
O
C. Stored data are made up of only two different values.
D. They are vulnerable to hackers and viruses.
Answer:
D
Explanation:
Let's analyze each option.
A "Multiple copies of the stored data take up very little space."
This is actually true, and it is a positive aspect, as stored digital data does not need any "physical space", it only needs memory and not a lot of it.
So storing data digitally is way more efficient than storing analog data.
B: "They lose quality when they are copied several times."
The data shouldn't change when it is copied, so you should not see a lose in quality.
C: "Stored data are made up of only two different values."
True, but as we know, we can define a lot of things with only two values (zeros and ones), so this is not really a disadvantage.
D: "They are vulnerable to hackers and viruses."
This is true, when you store your data digitally you become vulnerable to hackers stealing your data, so you need to get informatic security in order to protect your data. The same thing with viruses, if you have all your data stored in a given device, and the device becomes infected, there is a chance that you just lost all your data, so you need to have multiple backups of your important information, and again, some protection against viruses.
The correct option is D.
Answer:
D
trust me i just did it
Explanation: