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Paladinen [302]

3 years ago

12

The universe is filled with photons left over from the Big Bang that today have an average energy of about 4.9 ✕10-4 (correspond

ing to a temperature of 2.7 K).
What is the number of available energy states per unit volume for these photons in an interval of 4 ✕10-5eV?

1 answer:

motikmotik3 years ago

8 0

Answer:

The number of available energy is $4.820\times10^{45}$

Explanation:

Given that,

Energy $E=4.9\times10^{-4}\ J$

Temperature = 2.7 K

Energy states per unit volume $dE=4\times10^{-5}\ eV$

We need to calculate the number of available energy

Using formula of energy

$N=g(E)dE$

$N=\dfrac{8\pi\times E^2 dE}{(hc)^3}$

Where, h = Planck constant

c = speed of light

E = energy

Put the value into the formula

$N=\dfrac{8\pi\times(4.9\times10^{-4})^2\times4\times10^{-5}\times1.6\times10^{-19}}{(6.67\times10^{-34}\times3\times10^{8})^3}$

$N=4.820\times10^{45}$

Hence, The number of available energy is $4.820\times10^{45}$

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Mars2501 [29]

Answer with Explanation:

We are given that

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$F(sin\theta-\mu_kcos\theta)=\mu_kmg$

$F=\frac{\mu_kmg}{sin\theta-\mu_kcos\theta}$

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$P=\frac{\mu_kmg}{sin\theta-\mu_kcos\theta}v$

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3 years ago

A rock is dropped off a cliff and falls the first half of the distance to the ground in 2.0 seconds. how long will it take to fa

son4ous [18]

Answer:

The answer is 0.83 seconds.

Explanation:

The formula of free fall is following:

$h=1/2*g*t^2$

Where g=9.8 m/s^2 and t=2 seconds, the rock takes:

$h=1/2*9.8*2^2=19.6$

19.6 meters. This is the half distance of the cliff. The whole distance is 39.2 meters. So it takes:

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Rom4ik [11]

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3 years ago

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lyudmila [28]

Answer:

$y = 0.14 Cos\left ( 2.512x-34.66t \right )$

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