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Inflating balloon

  • Thread starter S_fabris
  • Start date
20
0
This is one of many postings from me this week :yuck: unfortunately I'm just not getting the correct answers...anyway here I go :

A toy balloon is inflated with helium at a constant pressure that is 4.2e5 Pa in excess of atmospheric pressure. If the balloon inflates from a volume of 1.4e-4m3 to 9.6e-4m3, how much work is done by the balloon on the surrounding air? answer in J
this is my work

P= 4.2e5Pa + 101300Pa
= 521 300 Pa
dV = (Vf-Vi) = (9.6e-4 - 1.4e-4)
= 0.00082m3

W= 521 300Pa x (0.00082m3)
427.466 J (incorrect on homework server)

I'm guessing it has something to do with the work on the surrounding air...I have been looking in my books and course notes for this and I can't find anything...can anybody help me out??

Any help is appreciated,
Sergio
 
1,860
0
Is this what the problem is supposed to be: A toy balloon is inflated with helium at a constant pressure that is [tex]4.2e^5[/tex] Pa in excess of atmospheric pressure. If the balloon inflates from a volume of [tex]1.4e^{-4}m^3[/tex] to [tex]9.6e^{-4}m^3[/tex], how much work is done by the balloon on the surrounding air? answer in J

(?)
 
20
0
Yes thats exactly the question on my homework page :)
 
20
0
Hey we finally got the answer...for the pressure...do not add the atmospheric pressure...simply use the one in the question

THank you for your time

Sergio
 

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