Physics - Fluid Question with Solution | TestHub

A hot air balloon is carrying some passengers, and a few sandbags of mass$1 \mathrm{kg}$each so that its total mass is$480 \mathrm{kg}$. Its effective volume giving the balloon its buoyancy is$V$. The balloon is floating at an equilibrium height of$100 \mathrm{m}$. When$N$number of sandbags are thrown out, the balloon rises to a new equilibrium height close to$150 \mathrm{m}$with its volume$V$remain unchanged. If the variation of the density of air with height$h$from the ground is$\rho \left(h\right)={\rho }_0{e}^{-\frac{h}{h_0}},$where${\mathrm{\rho }}_0=1.25 \mathrm{kg} {\mathrm{m}}^{-3}$and$h_0=6000 \mathrm{m},$the value of$N$is _________.