## helium balloon

I can't seem to figure this simple helium balloon problem out? I would really appreciate some help? Thanks!

Estimate the volume of a helium-filled balloon at STP if it is to lift a payload of 500 kg. The density of air is 1.29 kg/cubic meter and helium has a density of .178 kg/cubic meter.

I think you use a formula like force bouyancy equals density of air times volume times gravity????????? but not quite sure.

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 let V : Volume a= density of air b= density of He we have Code:  V*a=500*103+V*b
 How are you supposed to solve this equation with two unknowns?

## helium balloon

only V is unknown

 How do you solve V(1.29)= 500000+V(0.178) and is this really your answer?????????

 Originally posted by nsw How do you solve V(1.29)= 500000+V(0.178) and is this really your answer?????????
sorry the units of density are in Kg/m^3 so the equation will be

(1.29-0.178)V=500

V=450 m3

 Where does the 500 come from?
 isn't it the weight of the payload
 Oh Yah! Thanks a Bunch!
 The values: Balloon diameter : 100 feet Balloon weight : 10,000 pounds Payload weight : 6,000 pounds Lifting gas : Helium Air density at ground level : .0625 lbs/cubic foot Temperature is constant At what altitude does the balloon fly? So far I've got: h = alpha [0.862 - (16,000 lbs/ mass of air)] I'm not even sure what the variables are, I was given 47 different formulas to determine the answer to this question, none of which are helping whatsoever.

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