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Degger [83]
3 years ago
8

Assuming that 10.0% of a 100 W light bulb's energy output is in the visible range (typical for incandescent bulbs) with an avera

ge wavelength of 580 nm, and that the photons spread out uniformly and are not absorbed by the atmosphere, how far away (in km) would you be if 468 photons per second enter the 3.30 mm diameter pupil of your eye
Physics
1 answer:
Verizon [17]3 years ago
5 0

Answer:

Explanation:

10% of 100 W = 10 W .

energy of each photon = hν , h is plank's constant and ν is frequency

= hc / λ , c is velocity of light , λ is wavelength

wavelength given λ  = 580 x 10⁻⁹ m .

energy of each photon = 6.6 x 10⁻³⁴ x 3 x 10⁸ / 580 x 10⁻⁹

= .034137 x ⁻¹⁷ J

no of photons in 10 W

= 10 /  .034137 x ⁻¹⁷

= 292.9 x 10¹⁷

If d be the required distance

no of photons per unit area per second  at distance d

= 292.9 x 10¹⁷ / 4πd²

no of photons through the area of eye

= π x (1.65 x 10⁻³)² x 292.9 x 10¹⁷ / 4πd²

= 199.355 x 10¹¹ / d²

199.355 x 10¹¹ / d² = 468 ( given )

d² = 199.355 x 10¹¹ / 468

= .42597 x 10¹¹

= 42597 x 10⁶

d = 206.4 x 10³ m

= 206.3 km.

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John ( body mass= 65 kg) is taking off for a long jump . Horizontal accerleration ax is 5m/s^2 and vertical acceleration ay is 0
cestrela7 [59]

Answer:

(a) The horizontal ground reaction force  F_{g,x}=325\, N

(b)  The vertical ground reaction force F_{g,y}=696\, N

(c)   The resultant ground reaction force F_g=768\, N

Explanation:  

Given

John mass , m = 65 kg

Horizontal acceleration , a_x= 5.0 \frac{m}{s^{2}}

Vertical acceleration , a_y=0.9 \frac{m}{s^{2}}

(a) Using Newton's 2nd law in horizontal direction

F_{g,x}=ma_x

=>F_{g,x}=65\times 5\, N=325\, N

Thus the horizontal ground reaction force  F_{g,x}=325\, N

(b) Using Newton's 2nd law in vertical direction

F_{g,y}-mg=ma_y

=>F_{g,y}=mg+ma_y

=>F_{g,y}=65\times (9.81+0.9)\, N=696\, N

Thus the vertical ground reaction force F_{g,y}=696\, N

(c)  Resultant ground reaction force is

F_g=(F_{g,x}^{2}+F_{g,y}^{2})^{\frac{1}{2}}

=>F_g=(325^{2}+696^{2})^{\frac{1}{2}}\, N=768\, N

=>F_g=768\, N

Thus  the resultant ground reaction force F_g=768\, N

5 0
3 years ago
How much heat is released when a 10.0-g sample of iron cools from 75.0°c to 25.5 °c? the specific heat capacity of iron is 0.449
GalinKa [24]
M = 10.0 g, the mass of the iron sample
ΔT = 75 - 25.2 = 49.5°C, the decrease in temperature
c = 0.449 J/(g-°C), the specific heat of iron

The heat released is
Q = m*c*ΔT
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Answer: 222.3 J (nearest tenth)

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3 years ago
Which term describes an advantage of wind energy?
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The answer is "D". This is because wind is very abundant on earth...

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3 years ago
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A pair of narrow slits, separated by 1.8 mm, is illuminated by a monochromatic light source. Light waves arrive at the two slits
Nastasia [14]

Answer:

750 nm

Explanation:

d  = separation of the slits = 1.8 mm = 0.0018 m

λ = wavelength of monochromatic light

D  = screen distance = 4.8 m

y = position of first bright fringe = \frac{1cm}{5 fringe} = \frac{0.01}{5} = 0.002 m

n  = order = 1

Position of first bright fringe is given as

y = \frac{nD\lambda }{d}

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3 0
3 years ago
What was the main view how the world worked geologically prior to the 1960s? It was generally believed that continents and ocean
attashe74 [19]

Answer:

It was generally believed that mountains were produced by vertical forces

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                   The main view of the world worked geologically prior to the 1960s was that the mountains were formed by the vertical forces of nature.

                    The early people prior to 1960s believed in many different natural phenomenons and they give their own reasons for their occurrence. But later many researchers and geophysicists studied the formation of the earth and came with possible answers to these questions.

Thus the answer is  

" It was generally believed that mountains were produced by vertical forces."

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3 years ago
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