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3 years ago

PLEASE HELP. HOW DO U CALCULATE??

Physics

1 answer:

tatyana61 [14]3 years ago

5 0

-- The energy of one photon is (h · frequency of the light)

' h ' is 6.626 × 10⁻³⁴ m²-kg/s ("Planck's Constant")

-- The question doesn't tell you the frequency of the light from the LED, but it tells you the wavelength, and

Frequency = (speed of light) / (wavelength) .

-- Now you have everything you need to calculate the energy carried by one photon from the LED.

-- The power of the light from the LED is 120 milliwatts. That's 0.120 Joule of energy per second.

Now you should be able to find the number of photons per second. It's going to be (0.120 Joule) / (energy carried by one photon) .

When I scribbled it out on a scrap of scratch paper, I got 3.853 x 10³⁸ photons, but you'd better really check that out.

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What are gamma rays? How are they used?

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2 years ago

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Identify the law, write the equation and calculate the answer to the problem below.

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Find refractive index first

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1 year ago

How does adding more of a substance affect it's density?

fomenos

I’m going to use molasses as an example of a substance.

The mass and volume both change when changing the amount of molasses.
However, the density does not change. This is because the mass and volume increase at the same rate/proportion!

Even though there is more molasses (mass) in test tube A, the molasses also takes up more space (volume). Therefore, the spacing between those tiny particles that make up the molasses is constant (does not change).

The size or amount of a material/substance does not affect its density.

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3 years ago

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A person of mass 70 kg stands at the center of a rotating merry-go-round platform of radius 2.9 m and moment of inertia 900 kg⋅m

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Explanation:

It is given that,

Mass of person, m = 70 kg

Radius of merry go round, r = 2.9 m

The moment of inertia, $I_1=900\ kg.m^2$

Initial angular velocity of the platform, $\omega=0.95\ rad/s$

Part A,

Let $\omega_2$ is the angular velocity when the person reaches the edge. We need to find it. It can be calculated using the conservation of angular momentum as :