Question

Consider a helium balloon with volume 2.1 L.

Part (a) Calculate the buoyant force on the balloon, in newtons. Use 1.29 kg/m^3 for the density of air.
Part (b) Given the mass of the rubber in the balloon is 1.3 g, what will be the net force, in newtons, in the vertical direction (taking up as positive) on the balloon if it is released? Neglect the volume of the rubber, and use 0.18 x 10^-3 g/cm^3 for the density of helium.

Answer 1

The net force is 26.52 N

Step-by-step explanation:

Given that,

Volume of balloon = 2.1 L

Density of air = 1.29 kg/m³

Mass = 1.3 g

Density of helium
`\rho'= 0.18*10^(-3)\ g/cm^3`

(a). We need to calculate the buoyant force on the balloon

Using formula of buoyant force

`F_(b)=\rho V g`

Put the value into the formula

`F_(b)=1.29**2.1*9.8`

`F_(b)=26.54\ N`

(b). We need to calculate the net force

Using formula of net force

`F_(net)=F_(b)-(V*\rho'+m)* g`

`F_(net)=26.54-(2.1*10^(-3)*0.18*10^(-3)+0.0013)*9.8`

`F_(net)=26.52\ N`

Hence, The net force is 26.52 N.