To enhance heat rejection from a spacecraft, an engineer proposes to attach an array of rectangular fins to the outer surface of the spacecraft and to coat all surfaces with a material that approximates blackbody behavior. Consider the U-shaped region between adjoining fins and subdivide the surface into components associated with the base (1) and the side (2). Obtain an expression for the rate per unit length at which radiation is transferred from the surfaces to deep space, which may be approximated as a blackbody at absolute zero temperature. The fins and the base maybe assumed to be isothermal at a temperature T. Comment on your result. Does the engineer's proposal have merit

Answer:

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Explanation:

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Answer:

Distance is 300 and displacement is 100

Explanation:

Distance= 100+100+100=300

Displacement=100

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Answer:

W' = 1.66 x 10¹⁴ N

Explanation:

First, we will calculate the mass:

[tex]W = mg[/tex]

where,

W = weight on earth = 690 N

m = mass = ?

g = acceleration due to gravity on earth = 9.8 m/s²

Therefore,

[tex]m = \frac{W}{g} = \frac{690\ N}{9.8\ m/s^2}\\\\m = 70.4\ kg[/tex]

Now, we will calculate the value of g on the neutron star:

[tex]g' = \frac{GM}{R^2}[/tex]

where,

g' = acceleration due to gravity on the surface of the neutron star = ?

G = Gravitational Constant = 6.67 x 10⁻¹¹ N.m²/kg²

M = Mass of the Neutron Star = 1.99 x 10³⁰ kg

R = Radius of the Neutron Star = 15 km/2 = 7.5 km = 7500 m

Therefore,

[tex]g' = \frac{(6.67\ x\ 10^{-11}\ N.m^2/kg^2)(1.99\ x\ 10^{30}\ kg)}{(7500\ m)^2}\\\\g' = 2.36\ x\ 10^{12}\ m/s^2[/tex]

Therefore, the weight on the surface of the neutron star will be:

[tex]W' = mg'\\W' = (70.4\ kg)(2.36\ x\ 10^{12}\ m/s^2)[/tex]

W' = 1.66 x 10¹⁴ N

Answer:

the maximum voltage induced in the coil is 2.574 × 10⁻⁵ V

Explanation:

Given the data in the question;

Number of turns N = 10

major axis Ma = 13 cm = 0.13 m

a = 0.13/2 = 0.065 m

Minor axis Mi = 6 cm = 0.06 m

b = 0.06/2 = 0.03 m

we know that; 1 RPM = 0.10472 rad/s

rate of rotation R = 73rpm = 7.64 rad/s

Magnetic field = 55 uT

we know that, Area of ellipse = π × a × b

we substitute

A = π × 0.065 m × 0.03 m

A = 0.006126 m²

so

Maximum Voltage = N × Area × Magnetic field × rate of reaction

we substitute

Maximum Voltage = 10 × 0.006126 × ( 55 × 10⁻⁶ ) × 7.64

Maximum Voltage = 2.574 × 10⁻⁵ V

Therefore, the maximum voltage induced in the coil is 2.574 × 10⁻⁵ V

Mimicry. This is when oraganisms imitate another oraganism whether it be physical or behavoioral.

Answer:

1. B. The person and the Earth

2. This is because the energy gained by the person equals the energy lost by the earth,

Explanation:

1.

B. The person and the Earth

This is because the person and the earth both represent a system. A system consists of more than one item. A system consists of two or more items interacting with each other.

2. This is because, the energy of an isolated system is conserved according to the second law of thermodynamics which states that in an isolated system, energy can neither be created nor destroyed. So, there is an exchange of energy between the person and the Earth. So, the energy gained by the person at the new height equals the energy lost by the earth. And thus, the total energy of the system remains constant.

Answer:

1-1=0

Explanation:

ahriqqwertyuioo

I dont know you could start by asking your teacher, parent, and or siblings.

Ps the last part was a joke they never help.

Answer:

I think that perihelion is the point of the Earth's course that is close to the Sun. And i'm sure that aphelion in short is astronomy or otherwise the point in the orbit of a planet.

Explanation:

Hope this helps :)

Answer:

Explained below.

Explanation:

For a boat or any object to float on water, it's density must be less than that of water.

Now, when the maximum capacity of people to be carried by the boat is exceeded, it's possible that the maximum mass of people will also be exceeded depending on the mass of the people in the boat.

Now, we know that; density = mass/volume.

Thus, the higher the mass of the people, the higher the density and the higher the density, the more likely it is to be above that of water and the more likely it is to sink.

Answer:

please find your answer in the attached picture, along with explanation.

Answer:

Explanation:

The magnitude of the net force acting on an object is equal to the mass of the object multiplied by the acceleration of the object, as shown in this formula. We find its magnitude using the Pythagorean Theorem or the distance formula, and we find its direction using the inverse tangent function. Given a position vector →v=⟨a,b⟩, the magnitude is found by |v|=√a2+b2. The direction is equal to the angle formed with the x-axis, or with the y-axis, depending on the application.

Answer: hetero i think i dont know

Explanation:

Answer:

When two substances that cannot dissolve each other are mixed, a mixture is formed.

i hope this helps a little bit.

Answer:

Acceleration of the car = 5.51 m/s²

Explanation:

Given:

Initial speed of car = 0 m/s

Final speed of car = 27 m/s

Time taken by car = 4.9 seconds

Find:

Acceleration of the car

Computation:

Using first equation of motion

v = u + at

Where

v = Final velocity

u = Initial velocity

t = Time taken

a = Acceleration

So,

v = u + at

27 = 0 + a(4.9)

a(4.9) = 27

a = 5.51 m/s²

Acceleration of the car = 5.51 m/s²

Answer:

The distance between the helicopter and the man is increasing at a rate of 50.622 feet per second.

Explanation:

First, we create a geometric diagram representing the situation between man (point O),  helicopter (point P) and helipad (point H). The distance between man and helicopter is represented by Pythagorean Theorem:

[tex]x^{2}+y^{2} = r^{2}[/tex] (1)

Where:

[tex]x[/tex] - Distance between man and helipad, in feet.

[tex]y[/tex] - Distance between helipad and helicopter, in feet.

[tex]r[/tex] - Distance between man and helicopter, in feet.

By Differential Calculus, we derive an expression for the rate of change of the distance between man and helicopter ([tex]\dot r[/tex]), in feet per second:

[tex]2\cdot x\cdot \dot x + 2\cdot y\cdot \dot y = 2\cdot r\cdot \dot r[/tex]

[tex]\dot r = \frac{x\cdot \dot x + y\cdot \dot y}{r}[/tex]

[tex]\dot r = \frac{x\cdot \dot x + y\cdot \dot y}{\sqrt{x^{2}+y^{2}}}[/tex] (2)

Where:

[tex]\dot x[/tex] - Rate of change of the distance between man and helipad, in feet per second.

[tex]\dot y[/tex] - Rate of change of the distance between helicopter and helipad, in feet per second.

If we know that [tex]x = 40\,ft[/tex], [tex]y = 129\,ft[/tex], [tex]\dot x = 0\,\frac{ft}{s}[/tex] and [tex]\dot y = 53\,\frac{ft}{s}[/tex], then the rate of change of the distance between man and helicopter is:

[tex]\dot r = \frac{x\cdot \dot x + y\cdot \dot y}{\sqrt{x^{2}+y^{2}}}[/tex]

[tex]\dot r = 50.622\,\frac{ft}{s}[/tex]

The distance between the helicopter and the man is increasing at a rate of 50.622 feet per second.

Explanation:

I couldn't have information on this question.

Answer:

love is a feeling that you get for people that you care about.

Explanation:

Answer:

Love is a feeling of affection for someone, when you adore somebody.

I wish true love and soul mates were real ( •_•)

Answer:

Hello! Your answer would be, O False

Explanation:

Hope I helped! Brainiest plz!♥ Have a nice morning! Hope you make a 100%! -Abby

Answer:

False is the correct answer.

Explanation:

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Answer:

The solubility of KNO3 at 50 degrees C is 83 g/100 g water.

Explanation:

when u see the graph and by using graph reading techniques then u find the solubility.

Explanation:

The speed of light in vacuum is the same by all observers (2nd Principle). You would find that the starlight passes you at c. This is more than a thousand times faster than existing space craft.

According to all observers, the velocity of light in a vacuum will be the same (2nd Principle). You'd discover that the starlight is passing you at c. Compared to current spacecraft, this really is a thousand times faster.

The amount of the shift in approach per unit of time or the size of the displacement over time for an object can be used to describe speed, which would be a scalar quantity in everyday language and kinematics.

The maximum speed that can be maintained when a time period grows closer to zero is the starting speed.

By dividing the object's distance traveled by the duration of the interval, the mean pace of the object for the given period of time is calculated. Speed and velocity are not always the same thing.

To know more about Speed:

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Answer:

[tex]154.44\ \text{m/s}[/tex]

Explanation:

L = Length of guitar string = 0.66 m

Difference of fourth and first harmonic = 351 Hz

v = Wave propagation speed on the guitar strings

So,

[tex]\dfrac{4v}{2L}-\dfrac{v}{2L}=351\\\Rightarrow \dfrac{3v}{2L}=351\\\Rightarrow v=\dfrac{351\times 2\times 0.66}{3}\\\Rightarrow v=154.44\ \text{m/s}[/tex]

The wave propagation speed on the guitar strings is [tex]154.44\ \text{m/s}[/tex].

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Actually Welcome to the concept of resistors,

The equivalent circuit is given as,

1/Rp = 1/3 + 1/6 + 1/9

1/Rp = 6+3+2/18

1/Rp = 11/18

Rp = 18/11 ==> 1.63 ==> 1.6 ohms

hence the equivalent resistance of the circuit is 1.6 ohms

The equivalent resistance of the circuit is 1.6Ω. The correct option is B.

Ohm’s law state that ” At constant temperature, the current (I) flowing through a conductor is directly proportional to the potential difference(V) across the two endpoints of the given conductor.”

I.e V ∝ I

V=IR

Where V= potential difference across the conductor.

I = current flowing through the conductor.

R= constant pf proportionality i.e resistance which unit is ohm(Ω).

There are two ways we can connect the resistors.

(i) series connection

If a number of resistors are said to be connected in series When the same current (I) flows through them.

Let R1, R2, and R3 be the resistors connected in series.

Then the R equivalent is

Req=R1+R2+R3

(ii) parallel connection

A number of resistors are said to be connected in parallel when the same potential difference(V) exists across each of them.

Let R1, R2, and R3 be the resistors connected in parallel.

Then the R equivalent is

1/Req=1/R1+1/R2+1/R3

In this question,

The three resistance connected in parallel by applying the above formula we get,

1/Req=1/R1+1/R2+1/R3

1/Req = 1/3 + 1/6 + 1/9      .................  (∵R1=3Ω,R2=6Ω AND R3=9Ω)

1/Req =11/18

Req=18/11

Req=1.6363Ω

Req≈1.6Ω

Therefore, The equivalent resistance of the circuit is 1.6Ω.

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Answer: A. It gives off a range of wavelengths of electromagnetic radiation that depends on its temperature.

Explanation: Quizzed

Answer:

The small intestine absorbs most of the nutrients in your food, and your circulatory system passes them on to other parts of your body to store or use. Special cells help absorbed nutrients cross the intestinal lining into your bloodstream.

Explanation:

Answer:

[tex]0.261\ \text{m}[/tex]

Explanation:

[tex]\Delta f[/tex] = Change in frequency = 2.1 Hz

[tex]f[/tex] = Frequency of source of sound = 440 Hz

[tex]v_m[/tex]= Maximum of the microphone

[tex]v[/tex] = Speed of sound = 343 m/s

[tex]T[/tex] = Time period = 2 s

We have the relation

[tex]\Delta f=2f\dfrac{v_m}{v}\\\Rightarrow v_m=\dfrac{\Delta fv}{2f}\\\Rightarrow v_m=\dfrac{2.1\times 343}{2\times 440}\\\Rightarrow v_m=0.8185\ \text{m/s}[/tex]

Amplitude is given by

[tex]A=\dfrac{v_m T}{2\pi}\\\Rightarrow A=\dfrac{0.8185\times 2}{2\pi}\\\Rightarrow A=0.261\ \text{m}[/tex]

The amplitude of the simple harmonic motion is [tex]0.261\ \text{m}[/tex].

Answer:

4.8 m/s

Explanation:

Given: angular velocity of wheel ω = 2.5 rev/sec

radius r = 30 cm

length of arrow = 24 cm

For arrow to pass through spinning ring it has to pass between any two spokes of the wheel.

angle between two spokes = π/4

time taken by a spook to reach the position of adjacent spoke t =θ/ω

=  π/4/(2.5×2π) = 1/20 sec

for the arrow to pass through the spokes of the wheel it should take time t <1/20 sec to pass through the wheel

a) therefore, minimum speed = (24/100)/(1/20) = 4.8 m/s

Answer:

The correct solution is "1.2 m".

Explanation:

The given values are:

Wavelength of waves,

λ = 1.5 m

Speed of waves on surface,

V = 2 m/sec

Speed of waves in water,

V₁ = 1.6 m/sec

As we know,

⇒  [tex]V=f\times \lambda[/tex]

or,

⇒  [tex]f=\frac{V}{\lambda}[/tex]

On substituting the values, we get

⇒      [tex]=\frac{2}{1.5}[/tex]

⇒      [tex]=1.33 \ Hz[/tex]

hence,

⇒  [tex]\lambda_1=\frac{V_1}{f}[/tex]

On substituting the values, we get

⇒       [tex]=\frac{1.6}{1.33}[/tex]

⇒       [tex]=1.2 \ m[/tex]

Answer:

The car must be moving away from the person.

Explanation:

From Doppler's Effect, we know that when a sound source moves towards a stationary observer, the apparent frequency of that sound increases. While the apparent frequency decreases if the source moves away from the stationary observer.

The audible range of frequencies for a human ear is 20 Hz to 20000 Hz. Therefore, in order for the sound of a loud speaker to be audible for the person, the frequency must decrease below 20000 Hz.

Due to this reason, the car must be moving away from the person.