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jeka94
3 years ago
6

It turns out that the depth in the ocean to which airborne electromagnetic signals can be detected grows with the wavelength. Th

erefore, 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
Physics
1 answer:
r-ruslan [8.4K]3 years ago
3 0

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.

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Does anyone know how to solve series parallel and combo circuits
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Answer:

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2 years ago
Air as an ideal gas enters a diffuser operating at steady state at 5 bar, 280 K with a velocity of 510 m/s. The exit velocity is
Nataly [62]

Answer:

Explanation:

Calculating the exit temperature for K = 1.4

The value of c_p is determined via the expression:

c_p = \frac{KR}{K_1}

where ;

R = universal gas constant = \frac{8.314 \ J}{28.97 \ kg.K}

k = constant = 1.4

c_p = \frac{1.4(\frac{8.314}{28.97} )}{1.4 -1}

c_p= 1.004 \ kJ/kg.K

The derived expression from mass and energy rate balances reduce for the isothermal process of ideal gas is :

0=(h_1-h_2)+\frac{(v_1^2-v_2^2)}{2}     ------ equation(1)

we can rewrite the above equation as :

0 = c_p(T_1-T_2)+ \frac{(v_1^2-v_2^2)}{2}

T_2 =T_1+ \frac{(v_1^2-v_2^2)}{2 c_p}

where:

T_1  = 280 K \\ \\ v_1 = 510 m/s \\ \\ v_2 = 120 m/s \\ \\c_p = 1.0004 \ kJ/kg.K

T_2= 280+\frac{((510)^2-(120)^2)}{2(1.004)} *\frac{1}{10^3}

T_2 = 402.36 \ K

Thus, the exit temperature = 402.36 K

The exit pressure is determined by using the relation:\frac{T_2}{T_1} = (\frac{P_2}{P_1})^\frac{k}{k-1}

P_2=P_1(\frac{T_2}{T_1})^\frac{k}{k-1}

P_2 = 5 (\frac{402.36}{280} )^\frac{1.4}{1.4-1}

P_2 = 17.79 \ bar

Therefore, the exit pressure is 17.79 bar

7 0
3 years ago
The speed of the 2 kg cart after 5 seconds is ? cm/s.
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3 0
3 years ago
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Explanation:

4 0
3 years ago
Vector ????⃗ has a magnitude of 16.6 and is at an angle of 50.5∘ counterclockwise from the +x‑axis. Vector ????⃗ has a magnitude
natka813 [3]

Answer:

For vector u, x component = 10.558 and  y component =12.808

unit vector = 0.636 i+ 0.7716 j

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Explanation:

Let the vector u has magnitude 16.6

u makes an angle of 50.5° from x axis

So u_x=ucos\Theta =16.6\times cos50.5=10.558

Vertical component u_y=usin\Theta =16.6\times sin50.5=12.808

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Making an angle with -15.3° from x axis

So horizontal component v_x=vcos\Theta =24.5\times cos(-15.3)=23.6316

Vertical component v_y=vsin\Theta =24.5\times sin(-15.3)=-6.464

So vector v will be 23.6316 i - 6.464 j

Unit vector of v =\frac{23.6316i-6.464}{\sqrt{23.6316^2+6.464^2}}=0.9645i-0.2638j

8 0
3 years ago
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