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fenix001 [56]
3 years ago
6

PLEASE HELP. HOW DO U CALCULATE??

Physics
1 answer:
tatyana61 [14]3 years ago
5 0

-- The energy of one photon is <em>(h · frequency of the light)</em>

' 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  

<em>Frequency = (speed of light) / (wavelength) </em>.

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

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

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


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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3 years ago
a train car of mass 444 kg moving at 5 m/s bounces into another car on the same tracks of mass 344 king. of the second car was m
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Answer:

3.7 m/s

Explanation:

M = 444 kg

U = 5 m/s

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u = - 5 m/s

Let the velocity of train is V and the car s v after the collision.

As the collision is elastic

By use of conservation of momentum

MU + mu = MV + mv

444 x 5 - 344 x 5 = 444 V + 344 v

500 = 444 V + 344 v

125 = 111 V + 86 v .... (1)

By using the formula of coefficient of restitution ( e = 1 for elastic collision)

e = \frac{V-v}{u-U}

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v = V + 10

Substitute the value of v in equation (1)

125 = 111 V + 86 (V + 10)

125 = 197 V + 860

197 V = - 735

V = - 3.7 m/s

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4 0
3 years ago
What holds the moon in place, orbiting around the Earth
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The Earth's gravity keeps the Moon orbiting us. It keeps changing the direction of the Moon's velocity. This means gravity makes the Moon accelerate all the time, even though its speed remains constant.

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2 years ago
Two ice skaters stand in the middle of an ice rink. Drew has a mass of 75 kg, and Lily has a mass of 55 kg. Drew holds Lily, and
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PART a)

Before Drew throw Lily in forwards direction they both stays at rest

So initial speed of both of them is zero

So here we can say that initial momentum of both of them is zero

So total momentum of the system initially = ZERO

PART b)

Since there is no external force on the system of two

so there will be no change in the momentum of this system and it will remain same as initial momentum

So final momentum of both of them will be ZERO

PART c)

As we know that momentum of both will be zero always

so we have

P_1 + P_2 = 0

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7 0
3 years ago
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tatyana61 [14]
<h2>Answer:</h2><h2>It is due to a refractment of light.</h2>

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3 years ago
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