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An underwater sound source emits waves of frequency 30 kHz in all directions. How does the intensity of the waves (in Watts/m2) vary with distance r from the source?a) 1/r^3
b) 1/r^2
c) 1/r
d) None of above

Answers

Answer 1
Answer:

When an underwater sound source emits waves of frequency 30 kHz in all directions, the intensity of the waves (in Watts/m2) vary with distance r from the source by the relation 1/r²

As the intensity mechanical sound wave is inversely proportional to the square of the distance from the source, therefore the correct option is B.

What is the Wavelength?

Wavelength can be understood in terms of the distance between any two similar successive points across any wave for example wavelength can be calculated by measuring the distance between any two successive crests.

It is the total length of the wave for which it completes one cycle.

The intensity of a mechanical wave is inversely proportional to the square of the distance from the source.

An underwater sound source emits waves of frequency of 30 kHz in all directions, the intensity of the waves (in Watts/m2) varies with distance r from the source by the relation 1/r², therefore the correct option is B.

Learn more about wavelength from here

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Answer 2
Answer: b or c not sure but try

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A gate with a circular cross section is held closed by a lever 1 m long attached to a buoyant cylinder. The cylinder is 25 cm in diameter and weighs 200 N. The gate is attached to a horizontal shaft so it can pivot about its center. The liquid is water. The chain and lever attached to the gate have negligible weight. Find the length of the chain such that the gate is just on the verge of opening when the water depth above the gate hinge is 10 m.

Answers

The length of the chain such that the gate is just on the verge of opening  is mathematically given as

l=8.58m

What is the length of the chain?

Generally, the equation for the   is mathematically given as

F'=\gamma hA

Therefore

9810*10* (\pi)/(4)1^2

Fh= 77048 N

Where

ycp-y=((\pi r^4)/(4))/(10*(\pi D^4)/(4))

ycp-y=0.00625

In conclusion, resultant force

x = F'' - W

x = 9810* 10*( \pi/4 )*0.25^2 *(10-l)-200

x = 4615.5-481.5 l

Therefore

77048* 0.00625 - 1 *(4615.5-481.5 l) = 0

l=8.58m

Read more about Lenght

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Answer:

Explanation:

given,

length of lever = 1 m

diameter of cylinder = 25 cm

weight of cylinder = 200 N

hydrostatic force

F_H=\gamma hA

      = 9810* 10* (\pi)/(4)1^2

      = 77048 N

now,

y_(cp)-\bar{y}= \frac{I}{\bar{y}A}

                    =  ((\pi r^4)/(4))/(10*(\pi D^4)/(4))

                    =  0.00625 m

Finding the resultant force

F = F_(buoyancy) - W

F = \gamma_(water)A(10-l)-W

F = 9810* 10* (\pi)/(4)0.25^2* (10-l)-200

F = 4615.5-481.5 l

taking moment about hinge

F_(H)* 0.00625 - 1 * F = 0

77048* 0.00625 - 1 *(4615.5-481.5 l) = 0

l = 8.58 m

Help!!! Need answer ASAP.

Answers

Answer:

Hey

Explanation:

Calculate the speed (in m/sec) of a wave with a wavelength of 2.1 meters and a period of 9.4 second.

Answers

Wave speed = (wavelength) x (frequency)

We know the wavelength, but we don't know the frequency. How can we find the frequency ?  "Here frequency frequency."

We know the period, and frequency is just (1 / period).  So . . .

Wave speed = (wavelength) / (period)

Wave speed = (2.1 meters) / (9.4 seconds)

Wave speed = (2.1 / 9.4) m/s

Wave speed = 0.223 m/s

According to the U.S. Green Building Council, what percentage of the world’s energy use and greenhouse gas emissions can be attributed to buildings?

Answers

According to the US green building council, the US building account for 39% of world primary energy consumption . Electricity has approximately 78% of total building energy consumption and also contributes to GHG emissions

Answer:

40%

Explanation: United States Green Building Council is a body aimed at ensuring reduced green house gas emissions from activities taking place in building. they carry out surveys, carry out enlightenment activities and release the reports of and trending green house emission issues all these are to guarantee safe and healthy living for all. A total of 40% of Green house emissions are from buildings from the construction stage to it usage.

The electric field just above the surface of the charged drum of a photocopying machine has a magnitude E of 2.5 × 105 N/C. What is the surface charge density on the drum, assuming that the drum is a conductor?

Answers

Answer:

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Explanation:

Given data

Electric Field E=2.5×10⁵ N/C

To find

Charge Density

Solution

From definition of charge density we know that:

Charge Density=Electric field×Permttivity

Where Permttivity ∈₀=8.85×10⁻¹²C²/N.m²

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Answers

The answer is Adiabatic
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