Question

a)Calculate the buoyant force (in N) on a 2.70 L helium balloon.

b)Given the mass of the rubber in the balloon is 1.70 g, what is the net vertical force (in N) on the balloon if it is let go? You can neglect the volume of the rubber.

N (upward)?

Answer 1

a) Buoyant force FB= [V = volume of body inside the fluid]

Density of air = 1.225 kg/m3

volume inside air is = V = 2.7 x 10-3 m3.

therefore, buoyant force FB = [answer]

b) weight of baloon = 1.7 x 10-3 x 9.81 = 0.0167 N

weight of helium gas = density of helium x volume x g = 0.178 x 2 x 10-3 x 9.81 = 0.00349 N

Net force = Buoyant force - weight of baloon - weight of gas

= FB - Wbaloon - Wgas = 0.0324 - 0.0167 - 0.00349 = 0.0122 N [answer]

=