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lorasvet [3.4K]

3 years ago

14

Human fingers are very sensitive, detecting vibrations with amplitudes as low as 2.0x10^-5m. Consider a sound wave with a wavele

ngth exactly 1000 times greater than the lowest amplitude detectable by fingers. What is this waves frequency

1 answer:

Kobotan [32]3 years ago

3 0

Answer:

18,850 Hz

Explanation:

We need to figure out the wavelength of the sound wave.

Thus,

Wavelength = 1000 * Lowest Amplitude Wave

Wavelength = 1000 * 2.0 * 10^(-5)

Wavelength = 0.02

Or,

$\lambda=0.02$

Now, we need the frequency of this wave. It goes by the formula:

$f=\frac{v}{\lambda}$

Where

f is the frequency in Hz

v is the speed of sound in air (to be 377 m/s)

$\lambda$ is the wavelength (we found to be 0.02)

Substituting, we find the frequency:

$f=\frac{v}{\lambda}\\f=\frac{377}{0.02}\\f=18850$

The wave has frequency of 18,850 Hz

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OLga [1]

Answer:

$\theta = 106.3 degree$

Explanation:

As we know that

$\vec w = -\hat i + 7\hat j$

$\vec v = 7\hat i - \hat j$

also we know that

$\vec v. \vec w = -14$

it is given as

$\vec v. \vec w = (-\hat i + 7\hat j).(7\hat i - \hat j)$

$\vec v. \vec w = - 7 - 7 = -14$

also we can find the magnitude of two vectors as

$|v| = \sqrt{(-1)^2 + (7)^2}$

$|v| = \sqrt{50}$

similarly we have

$|w| = \sqrt{(7^2) + (-1)^2}$

$|w| = \sqrt{50}$

now we know the formula of dot product as

$\vec v. \vec w = |v||w| cos\theta$

$-14 = (\sqrt{50})^2cos\theta$

$\theta = cos^{-1}(\frac{-14}{50})$

$\theta = 106.3 degree$

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3 years ago

During a summer with little rainfall, your house on a hill slope experiences an interval during which your well runs dry. You ha

irina1246 [14]

Answer and Explanation:

You don't have water because of two possible reasons:

Because of the summer and the little rain, the underwater supply goes low.
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3 years ago

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How much heat is needed to raise the temperature of an empty 2.0 x 101 kg vat made of

scZoUnD [109]

Answer:

Q = 7272 Kilojoules.

Explanation:

<u>Given the following data;</u>

Mass = 2.0*101kg = 202kg

Initial temperature, T1 = 10°C

Final temperature, T2 = 90°C

We know that the specific heat capacity of iron = 450J/kg°C

*To find the quantity of heat*

Heat capacity is given by the formula;

$Q = mcdt$

Where;

Q represents the heat capacity or quantity of heat.

m represents the mass of an object.

c represents the specific heat capacity of water.

dt represents the change in temperature.

dt = T2 - T1

dt = 90 - 10

dt = 80°C

Substituting the values into the equation, we have;

$Q = 202*450*80$

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3 years ago

The gravitational force, F, between an object and the Earth is inversely proportional to the square of the distance from the obj

andreev551 [17]

<h2>Weight of astronaut 2450 miles above the Earth is 80.38 pounds</h2>

Explanation:

Given that gravitational force, F, between an object and the Earth is inversely proportional to the square of the distance from the object and the center of the Earth.

$F=\frac{k}{r^2}$

Where F is gravitational force between an object and the Earth, r is the distance from the object and the center of the Earth and k is a constant.

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In case 1 an astronaut weighs 209 pounds on the surface of the Earth,

$209=\frac{k}{4000^2}\\\\k=3.344\times 10^9$

Now we need to find weight of astronaut 2450 miles above the Earth

r = 4000 + 2450 = 6450 miles

$F=\frac{k}{6450^2}\\\\F=\frac{3.344\times 10^9}{6450^2}=80.38pounds$

Weight of astronaut 2450 miles above the Earth is 80.38 pounds

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3 years ago