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Tpy6a [65]
3 years ago
13

A person is standing outdoors in the shade where the temperature is 17 °C. (a) What is the radiant energy absorbed per second by

his head when it is covered with hair? The surface area of the hair (assumed to be flat) is 140 cm2 and its emissivity is 0.87. (b) What would be the radiant energy absorbed per second by the same person if he were bald and the emissivity of his head were 0.68?
Physics
1 answer:
Inessa05 [86]3 years ago
7 0

Answer:

a) 4.9W b) 3.82W

Explanation:

Stefan-Boltzmann law of radiation formulae:

Q/t (W) = sigma* e*A*T^4

Sigma = 5.67*10^-8 j/sm^2K^4 (Stefano Boltzmann constant)

e = emissivity

T = absolute temperature in kelvin and A = area in m^2

a) Q/t = 140/10000(m^2) * 0.87* 5.67* 10^-8* (290^4) = 4.9W

b) without hair the

Q/t = 140/ 10000(m^2) *0.68* 5.67* 10^-8* (290^4)

= 3.82W

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Read 2 more answers
<img src="https://tex.z-dn.net/?f=help%20%5C%3A%20mo%20%5C%3A%20ako%20%5C%3A%20please.." id="TexFormula1" title="help \: mo \: a
morpeh [17]

bentar mo numpang cerita nih

jadi gini

eist yg takut cerita horor Jan di baca

awokawokawok

ok lanjut ya dek ke cerita nya :)

jadi gini di jalan,jalan lalu lintas di kampung,,,,em kyk gini,,,hmm...... kyk mana ku ceritakan ya dek,,,,bingung aku soalnya,,,,,hmm....kyk gini lah,,,,,,,,jalan ini di tengah² kebun/ladang nah kan,,,,, sebenarnya ada dua jalan mo pergi keluar masuk dari kampung ku ke kampung tetanga jadi pejalan kaki lebih suka lewat jalan tikus,,,,,yg punya mobil,kereta/motor,sepeda lewat jalan yg horornl itu yg kubilng tadi itu......,,,,nah,,,,,aku sama kawan²ku lewat jalan yg horor ini,,,,,,nah ngk nyangka ku lihat sosok putih,,,,y aku masih berpikir itu ngk bener ,,,,,trussss dua hari kemudian aku mo pergi ke kampung tetanga pake sepeda,,,,aneh ny sepeda aku berat dan,,,da-dan aku lihat sosok putih itu lagi ,,,aku jadi ngebut deh ,,,,Untung aja aku ngk jatuh ,,,,,klw di bilang suruk² ,,,setiap jalan aku ntah sama siapa² ttp ku lihat sosok putih itu,,,,nah ketika sore² aku jalan sama temen ku,,,,,eh ku lihat lagi,,,,aku penasaran aku aja deh temen ku buat nengok,,,sosok putih itu,,,,ngk nyangka sosok putih itu udh ngk ada ,,,,aneh ngab :v

dah lah sampe disini aja dulu ya dek

byee byee

............. ... .

6 0
2 years ago
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