Lecture9-notes-worksheet - a sedentary person is...

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Phys 100 - Worksheet 7 Heat Transfer: Radiation Name: Student ID: Instructions: Discuss each question in small groups. V/rite on the back or an additional sheet for more space. 1) Radiation in Rooms (A-C: 15 min.; D,E: 15 min.) We have leamed that generally, a good absorber is also a good.emitter. This is expressed by having an emissivity close to the maximum of 1.0- We have also learned that most coÍìmon materials have a high emissivity in the infrared region (exception: highly reflective metals). We will explore some of the conr.qu"n"ãs on this worksheãt. A) Imagine you stand in your underwear in your room. at33 "C. How much power do you radiate? ?: ÇeÅTq = å emitted radiation? #r î (Ç-Ç,) Your skin temperature is roughly î=lî*' Ir,- T = 3úr 4-, ) How many kcals would you need to consume each day to make up for the radiated þ cr.- power. C) We know that the metabolic power of
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Unformatted text preview: a sedentary person is approximately l00V/, corresponding to - 2000 kcal burned in24 h. What is the reasorfor the différence between the radiated power and the metabolic power? (clickers) aM/ rat_lul,on D) If the room is kept at 200c,how much power does each square meter of its wall Erface emit? How much power does each squa.re meter absorb? /ç=f.*¿ F= zqg\ { = l.r¡ ($tukerL ?= ^+= fu' *?*È ? g k"ow-E) V/e know that heat is lost from the room by heat conduction. How does the amount compare to the absorbed and emitted radiation? (Make a reasonable assumption for an insulated wall.) Is it (much) larger, comparable, or (much) smaller than the absorbed and emitted heat due to radiation. Can we say that there is a balance between absorbed and k= o'oåå l-= 9'I Y^ lr - I ,^-r af = lot< : how Ttt+x2lor....
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This note was uploaded on 05/19/2011 for the course PHYS PHYS 100 taught by Professor Lioudmila during the Winter '10 term at UBC.

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