It turns out that the depth in the ocean to which airborne electromagnetic signals can be detected grows with the wavelength. Therefore, the military got the idea of using very long wavelengths corresponding to about 30 Hz to communicate with submarines throughout the world. If we want to have an antenna that is about one-half wavelength long, how long would that be

Answers

Answer 1

Wavelength = speed / frequency.

Wavelength = 3x10^8 m/s / 30 hz

Wavelength = 10 million meters

1/2 wavelength = 5 million meters

(that's about 3,100 miles)

I'm pretty sure the frequency is wrong in the question.

I think it's actually 30 kHz, not 30 Hz.

That makes the antenna about 3.1 miles long.


Related Questions

Light containing two different wavelengths passes through a diffraction grating with 1,250 slits/cm. On a screen 17.5 cm from the grating, the third-order maximum of the shorter wavelength falls midway between the central maximum and the first side maximum for the longer wavelength. If the neighboring maxima of the longer wavelength are 8.44 mm apart on the screen, what are the wavelengths in the light

Answers

Answer:

[tex]\lambda_s =6.43*10^-4m[/tex]

Explanation:

From the question we are told that:

Diffraction grating [tex]N=1250slits/cm[/tex]

Distance b/w Screen and grating length [tex]d_{sg}=17.5 cm[/tex]

Distance b/w neighboring maxima and Screen [tex]d_{ms}=8.44[/tex]

 

Generally the equation for grating space is mathematically given by

[tex]d(g)=\frac{1}{N}[/tex]

[tex]d(g)=\frac{100}{1250}[/tex]

[tex]d(g)=0.08[/tex]

Generally the equation for small angle approximation is mathematically given by

[tex]\triangle y=\frac{\lambda d}{L}[/tex]

Therefore for longest wavelength

[tex]\lambda _l=\frac{8.44*10^{-3}*(0.08)}{0.175m}[/tex]

[tex]\lambda _l=3.858*10^{-3}[/tex]

Therefore the third order maximum equation for the shorter wavelength as

[tex]\lambda_s =\frac{1}{6} \lambda_l[/tex]

[tex]\lambda_s =\frac{1}{6} (3.858*10^-^3)[/tex]

[tex]\lambda_s =6.43*10^-4m[/tex]

The wavelengths in the light is given as

[tex]\lambda_s =6.43*10^-4m[/tex]

The Brazilian rain forest is an area with significant biodiversity. As the rain forest is replaced with agricultural land, it is reasonable to predict a reduction in -

Answers-
A: consumption of solar energy.
B: sustainability over time.
C: precipitation levels.
D: average daily temperature.

Answers

B I think I’m not sure tho

Answer:

Bb

Explanation:

A hand dryer blows heated air downwards out of the exit duct at a velocity of 4 m/s. The temperature and density of the ambient air at the inlet are 15 C and 1.23 kg/m3, while at the outlet it has temperature 35 C and density 1.15 kg/m3 The blower power is 10.0 W and the heater power is 715 W. Consider the inlet to be at the large mass of ambient air which has negligible velocity.
a) What is the pressure at the outlet? 4 m/s, 35 C
b) You will be applying the energy equation. Why can you ignore any height differences in this situation?
c) If the specific heat of air C-1000 J/(kg K), where Δυ-C Δ T, find the change in internal energy per unit mass from the inlet to outlet.
d) Find the mass flow rate through the dryer.
e) What is the power loss in the system?
f) What is the loss in the system?
g) What is the head loss in the system?
h) What is the total loss coefficient of the system, referred to the outlet velocity?
i) If there were no heater, would the temperature of gas at the outlet be higher, the same, or lower than the inlet? Explain why.

Answers

Answer:

nzkdjdksishdjsdjjdjnzkskejeoueeuieeoyrie ryrhdhcksodopdncndnszdkhfoeosheiwuef wokxkzdkjdoeehxjbxbdkeiehdhdhddjjddjdhhdhdhhhjdhfjdjjfjddhdheudiwiehdbejwowud

Explanation:

isos

need help ASAP!!!!!!!!!!!

Answers

Answer:

The equation says that due to variation in temperature is

delt T = .59 m/s / C = 16 C * .59 m/s = 9.44 m/s

So v = 332 m/s + 9.44 m/s = 341 m/s (to three significant figures)

a disk of a radius 50 cm rotates at a constant rate of 100 rpm. what distance in meters will a point on the outside rim travel during 30 seconds of rotation?​

Answers

Answer:

239 rpm

Explanation: So the distance covered in one minute is 75,000 centimeters. The diameter of the wheel is 100 cm, so the radius is 50 cm, and the circumference is 100π cm. How many of these circumferences (or wheel revolutions) fit inside the 75,000 cm? In other words, if I were to peel this wheel's tread from the cart and lay it out flat, it would measure a distance of 100π cm. How many of these lengths fit into the entire distance covered in one minute? To find out how many of (this) fit into so many of (that), I must divide (that) by (this), so:

100πcm/rev

75,000cm/min

​750 min rev≈238.7324146RPM

A mass MM uniform solid cylinder of radius RR and a mass MM thin uniform spherical shell of radius RR roll without slipping. If both objects have the same kinetic energy, what is the ratio of the speed of the cylinder to the speed of the spherical shell

Answers

Answer:

vcyl / vsph = 1.05

Explanation:

The kinetic energy of a rolling object can be expressed as the sum of a translational kinetic energy plus a rotational kinetic energy.The traslational part can be written as follows:

       [tex]K_{trans} = \frac{1}{2}* M* v_{cm} ^{2} (1)[/tex]

The rotational part can be expressed as follows:

       [tex]K_{rot} = \frac{1}{2}* I* \omega ^{2} (2)[/tex]

where I = moment of Inertia regarding the axis of rotation.ω = angular speed of the rotating object.If the object has a radius R, and it rolls without slipping, there is a fixed relationship between the linear and angular speed, as follows:

       [tex]v = \omega * R (3)[/tex]

For a solid cylinder, I = M*R²/2 (4)Replacing (3) and (4)  in (2), we get:

       [tex]K_{rot} = \frac{1}{2}* \frac{1}{2} M*R^{2} * \frac{v_{cmc} ^{2}}{R^{2}} = \frac{1}{4}* M* v_{cmc}^{2} (5)[/tex]

Adding (5) and (1), we get the total kinetic energy for the solid cylinder, as follows:

       [tex]K_{cyl} = \frac{1}{2}* M* v_{cmc} ^{2} +\frac{1}{4}* M* v_{cmc}^{2} = \frac{3}{4}* M* v_{cmc} ^{2} (6)[/tex]

Repeating the same steps for the spherical shell:

        [tex]I_{sph} = \frac{2}{3} * M* R^{2} (7)[/tex]  

       [tex]K_{rot} = \frac{1}{2}* \frac{2}{3} M*R^{2} * \frac{v_{cms} ^{2}}{R^{2}} = \frac{1}{3}* M* v_{cms}^{2} (8)[/tex]

      [tex]K_{sph} = \frac{1}{2}* M* v_{cms} ^{2} +\frac{1}{3}* M* v_{cms}^{2} = \frac{5}{6}* M* v_{cms} ^{2} (9)[/tex]

Since we know that both masses are equal each other, we can simplify (6) and (9), cancelling both masses out.And since we also know that both objects have the same kinetic energy, this means that (6) are (9) are equal each other.Rearranging, and taking square roots on both sides, we get:

       [tex]\frac{v_{cmc}}{v_{cms}} =\sqrt{\frac{10}{9} } = 1.05 (10)[/tex]

This means that the solid cylinder is 5% faster than the spherical shell, which is due to the larger moment of inertia for the shell.

Two identical loudspeakers are driven in phase by the same amplifier. The speakers are positioned a distance of 3.2 m apart. A person stands 5.0 m away from one speaker and 6.2 m away from the other. Calculate the second lowest frequency that results in destructive interference at the point where the person is standing. Assume the speed of sound to be 330 m/ s. A) 183 Hz B) 275 Hz C) 413 Hz D) 137 Hz E) 550 Hz

Answers

Answer:

C) 413 Hz

Explanation:

For destructive interference, the path difference ΔL = (n + 1/2)λ where ΔL = L₂ - L₁ where L₁ = person's distance from one speaker (the closer one) = 5.0m and L₂ = person's distance from other speaker (the farther one) = 6.2 m and λ = wavelength = v/f where v = speed of sound = 330 m/s and f = frequency

So, ΔL = (n + 1/2)λ

L₂ - L₁  = (n + 1/2)v/f

f = (n + 1/2)v/(L₂ - L₁)

At the second lowest frequency that results in destructive interference at the point where the person is standing, n = 1.

So,

f = (1 + 1/2)v/(L₂ - L₁)

f = 3v/2(L₂ - L₁)

Substituting the values of the variables into the equation, we have

f = 3v/2(L₂ - L₁)

f = 3(330 m/s)/2(6.2 m - 5.0 m)

f = 3(330 m/s)/2(1.2 m)

f = 990 m/s ÷ 2.4 m)

f = 412.5 Hz

f ≅ 413 Hz

When a car makes a sharp left turn, what causes the passengers to move toward the right side of the car? *

A centrifugal force
B inertia
C centripetal acceleration
D centripetal force

Answers

B, the body at rest becomes reluctant to start moving or a body in motion becomes

reluctant and stop moving once in motion in a straight line

the number of perpandicular components of a force is

Answers

answer. 2 components

one directed upwards, and the other directed rightwards

Find the wavelength of light which is capable of ionizing a hydrogen atom?

Answers

Answer:

The correct answer is -  91.4 nm

Explanation:

According to Bohr's model, the minimum wavelength to ionize Hydrogen atom from n= 1 state is expressed as:

(h×c)/λ=13.6eV

here,

h - Planck constant

c - the speed of light

λ - wavelength

Placing the value in the formula for the wavelength

(6.626×10^−34J.s × 3×10^8 m/s)/λ  =  13.6 ×1.6 × 10^−19 J

λ≈91.4nm

Thus, the correct answer would be = 91.4 nm

If an athlete runs the triathlon of 10 km in 2 hours, what is her average speed in kilometers per hour?

Answers

Answer: 5 km per hour

Explanation:

if in 10 km there is 2 hours, then 10 divided by 2 is 5.

In a nuclear fusion reaction, atoms:
split apart.
combine.
explode.
cool down.

Answers

The answer is combine
The correct answer is B. Combine

volcano has both useful and harmful effects give reason​

Answers

Answer:

harmful effects

1. that will cause air pollution

2. that will destroy our earth

Answer:

useful effects of volcano are :-

it makes soil fertile it provides valuable nutrients for the soil

harmful effects of volcano are:-

it makes air polluted it destroy the environment .

hope it is helpful to you ☺️

Please answer this for 15 points please don’t put in a link.

Answers

It’s b I took the test

Answer:

c. Double Replacement

Explanation:

As in Double Replacement reaction exchanges the cations (or the anions) of two ionic compounds.

Here, in BaCl2 , Ba has replaced with NO3 to form Ba(NO3)2

and in 2AgNo3 , Ag has replaced with Cl to form 2AgCl.

Which of these cubes absorb the most light?

Answers

Answera black cube or dark colors cause dark colors suck in heat

A 64.0 cm long cord is vibrating in such a manner that it forms a standing wave with two antinodes. (The cord is fixed at both ends.) Which harmonic does this wave represent

Answers

Answer:

the wave represents the second harmonic.

Explanation:

Given;

length of the cord, L = 64 cm

The first harmonic of a cord fixed at both ends is given as;

[tex]f_o = \frac{V}{2L}[/tex]

The wavelength of a standing wave with two antinodes is calculated as follows;

L = N---> A -----> N    +   N ----> A -----> N

Where;

N is node

A is antinode

L = N---> A -----> N    +   N ----> A -----> N =  λ/2  + λ/2

L = λ

The harmonic is calculated as;

[tex]f = \frac{V}{\lambda} \\\\f = \frac{V}{L} = 2(\frac{V}{2L} ) = 2(f_o) = 2^{nd} \ harmonic[/tex]

Therefore, the wave represents the second harmonic.

L = λ

If a 75 W lightbulb is 15% efficient, how many joules of light energy does the bulb produce every minute?

Answers

Answer:

1 W = 1 J / sec       Definition of watt is 1 joule / sec

So if a bulb uses 75 J / sec it must use

75 J/s * 60 sec / min = 4500 J/min    energy used by bulb

If bulb is 15% efficient then the light delivered is

P = 4500 J / min * .15 = 675 J / min

At noon, ship A is 110 km west of ship B. Ship A is sailing east at 20 km/h and ship B is sailing north at 15 km/h. How fast is the distance between the ships changing at 4:00 PM

Answers

Answer:

[tex]4.47\ \text{km/h}[/tex]

Explanation:

[tex]\dfrac{da}{dt}[/tex] = Rate at which the distance between A and starting point of B is changing = -20 km/h

[tex]\dfrac{db}{dt}[/tex] = Rate at which the distance of B is changing = 15 km/h

[tex]\dfrac{dc}{dt}[/tex] = Rate at which the distance between A and B is changing

Time after which the rate at which the distance between A and B is changing is 4 hours

Distance covered by A in 4 hours = [tex]20\times 4=80\ \text{km}[/tex]

a = Distance remaining to the start point of B = [tex]110-80=30\ \text{km}[/tex]

b = Distance covered by B in 4 hours = [tex]15\times 4=60\ \text{km}[/tex]

Distance between A and B after 4 hours

[tex]c=\sqrt{a^2+b^2}\\\Rightarrow c=\sqrt{30^2+60^2}\\\Rightarrow c=67.08\ \text{km}[/tex]

[tex]c^2=a^2+b^2[/tex]

Differentiating with respect to time we get

[tex]c\dfrac{dc}{dt}=a\dfrac{da}{dt}+b\dfrac{db}{dt}\\\Rightarrow \dfrac{dc}{dt}=\dfrac{a\dfrac{da}{dt}+b\dfrac{db}{dt}}{c}\\\Rightarrow \dfrac{dc}{dt}=\dfrac{30\times -20+60\times 15}{67.08}\\\Rightarrow \dfrac{dc}{dt}=4.47\ \text{km/h}[/tex]

The rate at which the distance between the ships is changing at 4 PM is [tex]4.47\ \text{km/h}[/tex].

A dog runs 51 m west to fetch a ball and brings it back only 27 m before stopping.
The total displacement of the dog is:

Answers

The answer is 88m cause that’s the total distance the dog had ran in total and if that’s not the answer it’s 24m cause that’s how much further he had to go to retrieve it all the way back to the same position

types of wave interactions include​

Answers

Reflection
Refraction
Diffraction
Hope this helps :))

Please solve for 15 points. Please don’t input a link.

Answers

Answer:

a). Single replacement.

Explanation:

Because one element replaces another element in a compound

Which runner finished the 100 m race in the least amount of time?
Ming



Which runner stopped running for a few seconds during the race?



At what distance did Anastasia overtake Chloe in the race?

Answers

1: Ming

2: Chloe

3: 40m

What is a transfer of energy called?
A. Displacement
B. Acceleration
C. Work
D. Torque

Answers

Your answer is c, work

An object, with mass 64 kg and speed 14 m/s relative to an observer, explodes into two pieces, one 2 times as massive as the other; the explosion takes place in deep space. The less massive piece stops relative to the observer. How much kinetic energy is added to the system during the explosion, as measured in the observer's reference frame

Answers

Answer:

 K_f = 1881.6 J

Explanation:

To solve this exercise, let's start by finding the velocities of the bodies.

We define a system formed by the initial object and its parts, with this the forces during the explosion are internal and the moment is conserved

initial instant. Before the explosion

        p₀ = M v₀

final instant. After the explosion

        p_f = m₁ v + m₂ 0

the moeoto is preserved

         p₀ = p_f

         M v₀ = m₁ v

         v = [tex]\frac{m_1}{M}[/tex]  v₀

in the exercise they indicate that the most massive part has twice the other part

         M = m₁ + m₂

         M = 2m₂ + m₂ = 3 m₂

         m₂ = M / 3

so the most massive part is worth

        m₁ = 2 M / 3

we substitute

        v = ⅔ v₀

with the speed of each element we can look for the kinetic energy

initial

         K₀ = ½ M v₀²

Final

         K_f = ½ m₁ v² + 0

         K_f = ½ (⅔ M) (⅔ v₀)²

         K_f = [tex]\frac{8}{27}[/tex] (½ M v₀²)

         K_f = [tex]\frac{8}{27}[/tex]  K₀

the energy added to the system is

         ΔK = Kf -K₀

         ΔK = (8/27 - 1) K₀

         ΔK = -0.7 K₀

         K_f = K₀ + ΔK

         K_f = K₀ (1 -0.7)

         K_f = 0.3 K₀

let's calculate

         K_f = 0.3 (½ 64 14²)

         K_f = 1881.6 J

Acellus
What are harmful substances in the air,
soil, and water called?
A. pollutants
B. toxins
C. carcinogens
D. mutants

Answers

I think it’s A
Hope that helped XD

explain the refraction of light on a glass slab​

Answers

Answer:

refraction is the change in direction of a wave passing from one medium to another or from a gradual change in the medium.

A 0.70-kg disk with a rotational inertia given by MR 2/2 is free to rotate on a fixed horizontal axis suspended from the ceiling. A string is wrapped around the disk and a 2.0-kg mass hangs from the free end. If the string does not slip then as the mass falls and the cylinder rotates the suspension holding the cylinder pulls up on the mass with a force of______

Answers

Answer:

The force will be "9.8 N".

Explanation:

The given values are:

mass,

m = 0.7 kg

M = 2

g = 9.8

Now,

⇒  [tex]\tau = T \alpha[/tex]

then,

⇒  [tex]\frac{1}{2}mR^2(\frac{1}{R}\frac{dv}{dt}) =M(g-a_t)R[/tex]

⇒  [tex]\frac{1}{2}m \ a_t=m(g-a_t)[/tex]

⇒  [tex]a_t=\frac{2g}{(\frac{m}{M} +2)}[/tex]

On substituting the values, we get

⇒      [tex]=\frac{2\times 9.8}{\frac{0.7}{2} +2}[/tex]

⇒      [tex]=8.34 \ m/s[/tex]

hence,

⇒  [tex]T=mg+M(g-a_t)[/tex]

On substituting the values, we get

⇒      [tex]=0.7\times 9.8+2(9.8-8.34)[/tex]

⇒      [tex]=6.86+2(1.46)[/tex]

⇒      [tex]=6.86+2.92[/tex]

⇒      [tex]=9.8 \ N[/tex]

If our atmosphere had a uniform density of 1.25 kg/m3 all the way up to a border with empty space above, that border would be Answer km above sea level. The pressure at sea level is 1 atm = 105 N/m2 and g = 10 m/s2. Enter your answer as an integer.

Answers

Answer:

The border is 8km above sea level.

Explanation:

We know that:

Density = 1.25 kg/m^3

Pressure = 10^5 N/m^2

g = 10m/s^2

Now, suppose that we have a virtual rectangle, such that its bases have an area of 1m^2 and the rectangle has a height equal to H.

This virtual figure has a volume V = 1m^2*H, and it is filled with air (which we know that has a density 1.25 kg/m^3)

Then the total mass inside that volume is:

M = (1.25 kg/m^3)*V = (1.25 kg/m^3)*(1m^2*H)

The weight of this mass is:

W = g*M = (10m/s^2)*(1.25 kg/m^3)*(1m^2*H)

And if we divide the weight in a given surface, let's say 1 m^2, we get the pressure per square meter, which we know is equal to  10^5 N/m^2

then:

P = 10^5 N/m^2 = (10m/s^2)*(1.25 kg/m^3)*(1m^2*H)*(1/m^2)

Whit this equation we can find the value of H.

10^5 N/m^2 = (10m/s^2)*(1.25 kg/m^3)*(1m^2*H)*(1/m^2)

10^5 N =  (10m/s^2)*(1.25 kg/m^3)*(1m^2*H)

(10^5 N)/(10 m/s^2) = (1.25 kg/m^3)*(1m^2*H)

(10^4 kg) = (1.25 kg/m^3)*(1m^2*H)

(10^4 kg)/( 1.25 kg/m^3) = 1m^2*H

8,000 m^3 = 1m^2*H

(8,000 m^3)/(1m^2) =H

8,000 m = H

And we want this answer in km, knowing that 1,000m = 1km

8,000m = 8km = H

The border is 8km above sea level.

Height of boundaries is 8.2 km

Given that:

Normal density = 1.25 kg/m³

1 atm = 101325 N/m²

Find:

Height of boundaries

Computation:

Pressure = Height × Density × Gravitational acceleration

101325 = Height × 1.25 × 9.8

101325 = Height × 12.25

Height of boundaries = 101325 / 12.25

Height of boundaries = 8271.42 m

Height of boundaries = 8.2 km

Learn more:

https://brainly.com/question/23358029

Daryl ties a rope to a brick and lifts the brick straight up. The free-body
diagram below shows the brick when it is suspended above the ground.
Force 1
Force 2
What is force 1 in this diagram?
O A. Friction
OB. Tension
O C. Normal force
O D. Weight

Answers

The force 1 is tension force.

To find the correct statement among all the options, we need to know more about friction, tension, normal force and weight.

What is friction?Friction force is found between two surfaces when one is kept or moved on another surface.It is directed opposite to the direction of motion.What is tension force?When any object is hanged by an thread or rope, that object exerts a force on that rope. This force is called as tensional force.It's directed from along the rope towards the point of hanging.What is normal force?When an object is kept on a surface, the surface exerts a force on the object to oppose the weight of the object which is the normal force.It's perpendicular to the surface that an object contacts.What is weight?Weight is the gravitational force exerted by earth on that object. It's always directed towards the center of the earth.

Thus, we can conclude that the correct option is (B).

Learn more about tension here:

https://brainly.com/question/2008782

#SPJ2

a train has an initial velocity of 30 m/s. If the train accelerates uniformly at a rate of 6.3 m/s ^ for 2.8 seconds what is the trains final velocity?

Answers

T

Answer:

the velocity is a second final to initial velocity of 39

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