FYKOS Year 32 Series 1 Problem 1 — baloons · FYKOS 32 #32.1.1

Physics · mechanics · thermodynamics

Problem

How many balloons of volume

V=10 \mathrm{\ell }

filled with helium of density

\rho _{\scriptscriptstyle \rm He} = 0{,}179 \mathrm{kg\cdot m^{-3}}

are needed to lift Filip, whose mass is

m_{\scriptscriptstyle \rm F} =80 \mathrm{kg}

, and keep him afloat in air of density

\rho _{v} =1{,}205 \mathrm{kg\cdot m^{-3}}

? How many would be necessary to lift Danka, who weighs

m_{\scriptscriptstyle \rm D} =50 \mathrm{kg}

? Neglect the mass of the empty balloons.