 #1
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Homework Statement:
 A hot air balloon has a volume of 2500 m^3 and the fabric and the passengers have mass of 800 kg. It is takingoff when the air around the balloon has a temperature of 10 degrees Celsius and a density of 1.29 kgm^3. Calculate the minimum temperature of the air inside the balloon for take off. Note that the pressure inside and outside the balloon must be equal, since the balloon is open at the bottom.
Relevant Equations:

pV=nRT
pV=1/3Nm<c^2>
<E_k>=1/2m<c^2>=3/2kT
p = 1/3 x density x <c^2>
First, I tried using the Archimedes principle and calculated the weight of the surrounding air displaced when taking off.
##W = 2500\times 1.29\times 9.81 = 31637.25 N##
But then, I got stuck and do not know how to proceed from here on.
I don't want the full solution yet but can I get some guidance/hints as to how to approach this question?
Thanks
##W = 2500\times 1.29\times 9.81 = 31637.25 N##
But then, I got stuck and do not know how to proceed from here on.
I don't want the full solution yet but can I get some guidance/hints as to how to approach this question?
Thanks