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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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How much time does it take a power drill accelerating at 64.3 rad/s2 to achieve
Diano4ka-milaya [45]

Answer;

= 0.244 seconds

Explanation;

500 rpm is equivalent to; 1500 × 2π radians per minute

   = 9424.8 rad/minute  

To get revolutions per second we divide by 60

  = 9424.8/60  

   = 157.08 radians per second.  

Then we divide by 64.3 rad/s^2 to get time;

    = 157.08/64.3

     = 0.244 seconds.

7 0
3 years ago
Read 2 more answers
The x-coordinates of two objects moving along the x-axis are given as a function of time (t). x1= (4m/s)t x2= -(161m) + (48m/s)t
Kitty [74]
The two displacement functions are
x₁ = 4t
x₂ = -161 + 48t - 4t²
where
x₁, x₂ are in meters
t is time, s

The distance between the two objects is
x = x₁ - x₂
   =  4t + 161 - 48t + 4t²
x = 4t² - 44t + 161

Write this equation in the standard form for a parabola.
x = 4[t² - 11t] + 161
  = 4[ (t - 5.5)² - 5.5² ] + 161
 x = 4(t-5)² + 40

Ths is a parabola that faces up and has its vertex (lowest point) at (5, 40).
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The graph of x versus t confirms the result.

Answer: The distance of the closest approach is 40 m.

5 0
3 years ago
A canoe floats in a lake. Inside the canoe is a 25 kg steel solid ball. If the ball is thrown into the lake, does the level of t
Rus_ich [418]

Answer:

Explanation:

volume of ball bearing = 4/3 π r³

= 4/3 x 3.14 x 1.5³

= 14.13 cc.

if D  be the density of steel , weight of the ball bearing

= 14.13 x D x g

For the first case , water will be displaced to keep it floating

weight of displaced water will be equal to weight of steel

weight of displaced water = 14.13 Dg

mass of displaced water = 14.13 D

volume of displaced water = mass / density of water

= 14.13 D / d                             ; (where d is density of water) .

Now when the steel ball bearing is dipped in water , it will displace water equal to its volume only and it will be drowned

its volume = 14 .13 cc

14.13 D / d  >  14.13  ( because D/d is more than one , since D > d )

volume of water displaced in first case is greater

water level will go up higher in first case .

Hence in the second case water level will go down .

Same will happen in case of 25 kg steel .

4 0
3 years ago
A hockey player is wearing ice skates and pushes against the wall propelling her backward on the ice. According to Newton's thir
Amiraneli [1.4K]

I do not know of the following in your class, but the wall is still and non-moving, while the hockey player is pushing off of it, as stated. So, this is not inertia, for a fact, because the wall is not moving towards the hockey player.

5 0
3 years ago
Only Wednesdays <br> Pls help
madreJ [45]
No, it should not be permitted. It can seriously damage one of the people participatings mind. It would overall not be good
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3 years ago
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