Helium Balloon Question!!! Hey I have a buoyancy question here, anyone know how to solve it? A 15 gram rubber balloon is filled with 18 L of Helium (density 0.179kg/m^3) and tied with a string to a child's wrist. Find the tension in the cord. The answer is 0.050N but what is the solution? Im not sure if yuo need it but the denisty of air is 1.29kg/m^3. Thanks. 2. Relevant equations Equations i used include F buoyancy = F tension + m helium * gravity + m balloon * gravity and F buoyancy = density * gravity * volume displaced 3. The attempt at a solution I tried to solve but got completely different answers, what is the volume displaced? is that the right thing to use?