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Cloud [144]
4 years ago
8

A surface receiving sound is moved from its original position to a position three times farther away from the source of the soun

d. The intensity of the received sound thus becomes
a. three times as high,
b. nine times as high.
c. nine times as low.
d.three times as low.
Physics
1 answer:
vazorg [7]4 years ago
6 0

Answer:

c. nine times as low.

Explanation:

Sound intensity is defined as the acoustic power transferred by a sound wave per unit of normal area to the direction of propagation:

I\propto \frac{1}{A}

Since the sound wave has a spherical wavefront of radius r, then the area is given by:

A=4\pi r^2

Here r is the distance from the source of the sound. Thus sound intensity decreases as:

I\propto \frac{1}{4\pi r^2}\\\\I'\propto \frac{1}{4\pi r'^2}\\\\I'\propto \frac{1}{4\pi (3r)^2}\\\\I'\propto \frac{1}{9} \frac{1}{4\pi r^2}\\\\I'\propto \frac{1}{9} I

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The amount of energy that must be absorbed or lost to raise or lower the temperature of 1 g of liquid water by 1°c _____.
Fiesta28 [93]

Answer:

4.2 J

Explanation:

Specific heat capacity: This is defined as the amount of a heat required to rise a unit mass of a substance through a temperature of 1 K

From specific heat capacity,

Q = cmΔt.............................. Equation 1

Where Q = amount of energy absorbed or lost, c = specific heat capacity of water, m = mass of water, Δt = Temperature rise.

Given: m = 1 g = 0.001 kg, Δt = 1 °C

Constant : c = 4200 J/kg.°C

Substitute into equation 1

Q = 0.001×4200(1)

Q = 4.2 J.

Hence the energy absorbed or lost = 4.2 J

6 0
3 years ago
William Ferrel:
balu736 [363]

Answer:

William Ferrel created a tide-prediction machine.

Explanation:

  • William Ferrel create a machine in late 19th century that was the best combination of mechanical parts and computer coding.
  • It was a mechanical analog computer that could predict the ebb of tides and even the height of tides that could be irregular.
  • It was widely used for marine networks and navigation. Later on many improvisations and additional features were added on it.
  • During the world war times, this tide prediction machine was of great use for military purpose.
3 0
3 years ago
What distance is covered by an airplane traveling at a velocity of 660 miles per hour in 3.5 hours?
N76 [4]

As per the question, the velocity of the airplane [v] = 660 miles per hour.

The total time taken by airplane [t] = 3.5 hours.

We are asked to determine the total distance travelled by the airplane during that period.

The distance covered [ S] by a body is the product of velocity with the time.

Mathematically distance covered = velocity × total time

                                                      S = v × t

                                                        = 660 miles/hour ×3.5 hours

                                                        = 2310 miles.

Hence, the total distance travelled by the airplane in 3.5 hour is 2310 miles.

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HELPPPP
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Answer:

A. nuclear fusion reactions

C. it's still hot from the big bang

Explanation:

The inside of the earth is hot due to some reasons. This heat provides the internal energy the drives processes within the earth interior. Here are some of the ways in which the heat has accumulated:

  • Nuclear reactions within the earth interior by fusion and other radioactive processes releases a large amount of heat.
  • Some heat accreted during the early formation of the earth and has not been lost till this day.
  • Heating due to friction

These are some of the sources of the earth's internal heat.

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3 years ago
Does potential energy increase,kinetic energy decrease when a book is placed on a shelf
DerKrebs [107]
Yes potential increases while kinetic decreases
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