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3 years ago

9

Describe the motion of the moon in space to produce the different phases of the moon.

1 answer:

ss7ja [257]3 years ago

4 0

Answer:

Moon slowly moves eastward, rising later each day and passing through its phases:

Explanation:

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In general, if a sound has intensity of β dB at 1 m from the source, at what distance from the source would the decibel level de

Tpy6a [65]

Answer: The required distance is given by

$r_2=1\text{ m}\cdot 10^\frac{\beta}{20}.$

Explanation: The sound intensity in dB is given by the formula

$\beta \text{ dB}=10\log\frac{I}{I_0}$

where $I_0$ is the hearing threshold in absolute units and $I$ is the absolute intensity of the sound which depends on the distance. In general, for two distances $r_1$ and $r_2$ we have that

$\frac{I(r_1)}{I(r_2)}=\frac{r_2^2}{r_1^2}=\left(\frac{r_2}{r_1}\right)^2.$

Now let us take $r_1=1\text{ m}$ and let $r_2$ be the required distance. We have

$\beta \text{ dB}=10\log\frac{I(r_1)}{I_0},\quad 0\text{ db}=10\log\frac{I(r_2)}{I_0}.$

Exponentiating these equations we obtain

$10^{\frac{\beta}{10}}=\frac{I(r_1)}{I_0},\quad 10^0=1=\frac{I(r_2)}{I_0}.$

Dividing them

$\frac{I(r_1)}{I(r_2)}=10^\frac{\beta}{10}.$

Using the previously stated identity

$\frac{r_2^2}{r_1^2}=10^\frac{\beta}{10}\Rightarrow r_2=r_110^\frac{\beta}{20}=1\text{ m}\cdot 10^\frac{\beta}{10}$

Now if we use the given example where $\beta=11$ we have

$r_2=1\text{ m}\cdot 10^{\frac{11}{20}}=3.55\text{ m}.$

7 0

3 years ago

Suppose that at room temperature, a certain aluminum bar is 1.0000 m long. The bar gets longer when its temperature is raised. T

Alja [10]

Answer:

The change of the bar's length is $3.9\times10^{-4} m$

Explanation:

The bar length is a function of temperature T above room temperature:

$L(T)=1.0000+2.4\times10^{-5} T$

So, if we evaluate at T= 16.1 C above room temperature

$L(16.1)=1.0000+2.4\times10^{-5} (16.1)$

$L=1.00039 m$

Now we can find the change of the bar length with the difference of L and Lo (the length at room temperature)

$L- L_0=1.00039-1.0000 = 3.9\times10^{-4} m$

7 0

3 years ago

An object that revolves around a planet is called a

ad-work [718]

A natural satellite. Or just a satellite.

6 0

3 years ago

Read 2 more answers

A mother is pulling a sled at constant velocity by means of a rope at 37°. The tension on the rope is 120 N. Mass of children pl

nordsb [41]

Answer:

Please find the complete solution in the attached file.

Explanation:

3 0

3 years ago

Your car is skidding to a stop from a high speed. name all the forces that apply

DerKrebs [107]

Normal force, weight, Kinetic friction, and air resistance are a few I think of the top of my head.
I hope this helps

6 0

3 years ago