In: Physics
The premise of Pixar’s movie Up is that balloons can lift a house. Well, let’s just see. Take the area of a two-bedroom house to be 72 m2, the height to be 4.5 m, and the mass to be 2300 kg (not including the air inside). Assume that we use industrial balloons that have a radius of 45 cm, can withstand 3 atmospheres of pressure at 21 °C, have coverings of 150 g, and are filled with helium. Take the density of air to be 1.225 kg/m3 and the molar mass of helium to be 4 g/mol.
a. How many moles of gas does each balloon hold?
b. What is the average force each particle exerts on the balloon wall? What is the average speed of the particles in the balloons?
c. Draw a free-body diagram for the house once the balloons lift it from the ground. Do not neglect any mass.
d. How many balloons need to be attached to the house to give it a = 0.75 m/s2?
e. Not wanting to go up to high, the owner of the house decides to release some balloons until a=0 in order to stop their ascent. Will this work? If so, how many balloons need to be released? If not, why?