Teaching Physics with the Physics Suite

Edward F. Redish

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Cats Up

In the Disney-Pixar movie Up, a disgruntled and bored old man attaches a large number of helium balloons to his house and floats away to have some adventures. This is shown in a clip from the movie's trailer at the left.

It's fairly difficult to see whether this is plausible by estimating the weight of a house -- and one would have to figure out whether the house had the structural strength to be able to be lifted from one point on the roof without breaking apart.

So let's do a simpler problem. Estimate how many helium balloons of the indicated size in the figure at the right* would be needed to lift the kitten. You can take the density of air to be ~ 1 kg/m3 and the density of helium to be about 1/7 that of air when both are at STP.

Do you need to worry about the weight of the balloons?

* From http://icanhascheezburger.com

Page last modified November 27, 2010: M29