If the Moon did not rotate at the same rate that it revolved, which of the following would be true?

Estimate the number of photons emitted per second from 1.0 cm2 of a person's skin if a typical emitted photon has a wavelength o

Diano4ka-milaya [45]

Answer:

2.63 x 10^18

Explanation:

A = 1 cm^2 = 1 x 10^-4 m^2

λ = 10,000 nm = 10,000 x 10^-9 m = 10^-5 m

T = 37 degree C = 37 + 273 = 310 k

Energy of each photon = h c / λ

where, h is the Plank's constant and c be the velocity of light

Energy of each photon = (6.63 x 10^-34 x 3 x 10^8) / 10^-5 = 1.989 x 10^-20 J

Energy radiated per unit time = σ A T^4

Where, σ is Stefan's constant

Energy radiated per unit time = 5.67 x 10^-8 x 10^-4 x 310^4 = 0.05236 J

Number of photons per second = Energy radiated per unit time / Energy of

each photon

Number of photons per second = 0.05236 / (1.989 x 10^-20) = 2.63 x 10^18

4 0

2 years ago

A large piece of jewelry has a mass of 132.6 g. a graduated cylinder initially contains 48.6 ml water. when the jewelry is subme

Lerok [7]

The density of the substance is 10.5 g/cm³.

The jewelry is made out of Silver.

Density ρ is defined as the ratio of mass m of the substance to its volume V. The cylinder contains a volume V₁ of water and when the jewelry is immersed in it, the total volume of water and the jewelry is found to be V₂.

The volume V of the jewelry is given by,

$V=V_2 -V_1$

Substitute 48.6 ml for V₁ and 61.2 ml for V₂.

$V=V_2 -V_1\\ =61.2 ml -48.6 ml\\ =12.6 ml$

calculate the density ρ of the jewelry using the expression,

$\rho =\frac{m}{V}$

Substitute 132.6 g for m and 12.6 ml for V.

$\rho =\frac{m}{V}\\ =\frac{132.6 g}{12.6 ml} \\ =10.5 g/ml$

Since $1 ml=1 cm^3$ ,

The density of the jewelry is 10.5 g/cm³.

From standard tables, it can be seen that the substance used to make the jewelry is silver, which has a density 10.5 g/cm³.

4 0

2 years ago

A figure shows a vertically moving block on the end of a cord. The graph next to the figure gives the vertical velocity componen

Sergio [31]

It should be 2/9/10 in functional form

3 0

2 years ago

When I wave a charged golf tube at the front of the classroom with a frequency of two oscillations per second, I produce an elec

borishaifa [10]

To solve the exercise it is necessary to take into account the concepts of wavelength as a function of speed.

From the definition we know that the wavelength is described under the equation,

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

Where,

c = Speed of light (vacuum)

f = frequency

Our values are,

$f = 2Hz$

$c = 3*10^8km/s$

Replacing we have,

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

$\lambda = \frac{3*10^8km/s}{2Hz}$

$\lambda = 1.5*10^8m$

Therefore the wavelength of this wave is $1.5*10^{8}m$

8 0

2 years ago

a man stands in a lift going downward with uniform velocity. he experiences a loss of weight at the start but not when lift is i

AnnyKZ [126]

Answer:

It is explained in the explanation section

Explanation:

When the lift starts going downwards, it will start accelerating downwards. After a while, it will start moving with a constant velocity.

Constant velocity means that acceleration is zero and so the man will not feel any weight loss.

Now, Once the lift achieves constant velocity the acceleration is zero hence he will not experience any weight loss.

However, when the lift is in uniform motion, the lift and the man will fall down with an acceleration(a) that is less than that due to gravity(g) . Thus, the man will feel an apparent weight F which is not equal to zero.

6 0

3 years ago

If the Moon did not rotate at the same rate that it revolved, which of the following would be true?​

If the Moon did not rotate at the same rate that it revolved, which of the following would be true?