ข้อสอบปี 1996
A hot -air balloon is floating in the atmosphere having temperature

and pressure
A burner was turned on and the temp. inside the ballon was increased from

to

. Assume
that the Volume

of the balloon doesn't change and the pressure inside balloon is

, the
same as the atmosphere pressure .When the Temp. increased from

to

,the mole of the
air inside it decreased from

to

.These quantities are expressed as
![n_{0} = [?] n_{0} = [?]](/forums/Sources/latex/pictures/b74d36175071da6cdd4bca0e9d1922b0.png)
and
![n_{1} = [?] n_{1} = [?]](/forums/Sources/latex/pictures/43bf2b2a77cba798d6399f20f242f2e6.png)
in term of R,Pressure ,Volume and Temperature. .If one denotes the mass of the air per mole by

and the gravitational acceleration by

, the climbing force exerted upon the ballon is the
resultant force of buoyancy

received by the ballon and the gravity

of
the air inside the balloon .
This climbing force of the original air per 1 mol (

)

,is written as [? ]

using

and
Supposing that

and

the climbing force

of the original air per 1 mol is able to lift a body having mass = [? ]kg
The Volume of the air of a mole is approximately 0.025

if
and

. This means that the volume of the balloon must exceed [?]

so that it lifts a body having mass 100 kg including the balloon itself.