## Can a house fly??? Can you fly???

April 7, 2010*Thanks to Jason studying maths & physics at University of Minnesota for this suggestion.*

Unless you have seen the animated movie **UP** ‘Can a house fly?’ is a funny question. The movie with the Boy Scout, Carl, and the grumpy old guy had quite a few people asking could a house fly?

We can do the maths, mathspigs! But why do the maths if someone has already done the hard work for you?

The X Change Files blog and Wired magazine have put together some fab calculations.

Unfortunately, all of their calculations are in American units but we can use their calculations as a guide. We will not include the weight of the balloons or string and we will assume the balloons are spherical so the answers are approximations and add a few more balloons to make the house & balloons more buoyant than air. Here is the information you need:

**Can you fly?**

We know humans can fly using helium balloons as 2nd July 1982 Larry Walters tied 45 weather balloons to a garden chair and flew to an altitude of 4,600m (15,000 ft). He carried a bbgun to shoot balloons for his descent but only hit a couple and dropped the gun. He flew for over 45 mins and was arrested on landing. Larry Walters link.

While I would advise mathspigs against such a stunt it is interesting to calculate how many balloons you would need to fly:

Don’t forget to add your weight in Kg.

Here is one of my favorite HOT AIR balloons called, wait for it, THE HOT HARE BALLOON.

I know it might detract somewhat from the excellent use of practical maths, but the director’s commentary for Up admits that they fudged the numbers and size of the balloons to get each shot looking ‘right’.

While I’m a big fan of scientific accuracy in movies, there is the odd occasion where realism has to take a back seat to artistic endevour.

This example could also be used for senior high school physics, under the guise of ‘find the maximum height reached by the house, expressed in terms of the volume and number of balloons, where the density of air with respect to altitude is f(X) and density of helium is f(Y)’

by Leeman April 16, 2010 at 2:22 amHi Leeman,

Wow! I love people with maths smarts. I don’t expect movies to be accurate but I’d use any trick in the book to get kids doing the maths. And if you can whip up the f(y) formula re: high school physics I’d love to see it.

by mathspig April 16, 2010 at 7:53 amThanks for your thoughts.

Mathspig