Pay load is defined as the difference between the mass of displaced air and the mass of the balloon. Calculate the pay load when a balloon of radius 10 m, mass 100 kg is filled with helium at 1.66 bar at 27∘C. (Density of air = 1.2kgm−3andR=0.083 bar dm3K−1mol−1).
Given,
Radius of the balloon, r = 10 m
∴ Volume of the balloon =43πr3
=43×227×103=4190.5m3(approx)
Thus, the volume of the displaced air is 4190.5m3.
Given,
Density of air =1.2kgm−3
Then, mass of displaced air =4190.5×1.2kg=5028.6kg
Now, mass of helium (m) inside the balloon is given by,
m=MpVRT
Here,
M=4×10−3kgmol−1
p=1.66 bar
V= Volume of the balloon
=4190.5m3R=0.083 bar dm3K−1mol−1T=27∘=300 K
Then, m=4×1.66×4190.5×1030.083×300=1117.5 kg (approx)
Now, total mass of the balloon filled with helium = (100 + 1117.5) kg
= 1217.5 kg
Hence, pay load = (5028.6 – 1217.5) kg= 3811.1 kg
Hence, the pay load of the balloon is 3811.1 kg.