## Essential University Physics: Volume 1 (3rd Edition)

We know that the balloon will lose its buoyancy when the force of gravity exceeds the force of the buoyancy of the balloon. Thus, we find: $\frac{4}{3}\pi(.14^3)(.18)g+.0016g +(6.3\times10^{-4})(n)g=\frac{4}{3}\pi(.14^3)(1.29)g \\ n =20$