Answer to Question #89096 in Physics for Evelyn Edmondson

Question

An empty rubber balloon has a mass of 12 grams. The balloon is filled with helium at STP. The helium filled balloon has a radius of 50 cm. What is the force of gravity on the balloon?

Answer 1

The  force of gravity on the balloon is

$$W=(m+m_{He})g=(m+\rho_{He} V)g$$

$$V=\frac{4}{3}\pi r^3$$

$$W=(m+m_{He})g=(m+\frac{4}{3}\pi r^3\rho_{He} )g$$

$$W=(0.012+\frac{4}{3}\pi (0.5)^3(0.1785) )9.8=1.0\ N$$