Physics Ch.4 Practice Passage Question 7

Post Reply
jmartin
Posts: 17
Joined: Sat Mar 03, 2018 12:55 pm

Physics Ch.4 Practice Passage Question 7

Post by jmartin » Tue Mar 27, 2018 11:18 am

The explanation for the correct answer given is "..we expect the final power radiation to be higher than the initial power radiation..". How do you find the final power radiation and initial power radiation?
NS_Tutor_Andrew
Posts: 520
Joined: Mon May 23, 2016 1:47 pm

Re: Physics Ch.4 Practice Passage Question 7

Post by NS_Tutor_Andrew » Wed Mar 28, 2018 12:23 pm

Hi jmartin,

This is based on the Stefan-Boltzmann law that's given at the end of the passage. This equation is too complicated to calculate with directly, but we can look at the logic of the equation to figure out how it responds to differences in body temperature (T) and the ambient temperature (Ta). The equation contains a term (T^4 - Ta^4). This is complicated to work with, but we can still recognize that this term is going to be larger when the difference between T and Ta is larger. Human body temperature is about 310 K, so decreasing the ambient temperature from 288 K to 272 K will increase the difference between T and Ta, thereby increasing P according to that equation.

Hope this helps clarify this question!!
Andrew D.
Content Manager, Next Step Test Prep.
jmartin
Posts: 17
Joined: Sat Mar 03, 2018 12:55 pm

Re: Physics Ch.4 Practice Passage Question 7

Post by jmartin » Fri Mar 30, 2018 1:22 pm

Thank you!
Post Reply