Answer:
40454.4 N
Step-by-step explanation:
mass, m = 320 kg
density of hot air, d = 1.19 kg/m^3
density of cold air, d' = 1.29 kg/m^3
Volume of the balloon, V = mass / density
V = 320 / (1.29 - 1.19)
V = 3200 m^3
So, buoyant force
F = Volume x density outside x gravity
F = 3200 x 1.29 x 9.8
F = 40454.4 N
thus, the buoyant force is 40454.4 N.