Pi Day: a day to think about whipping cream?
Pi Day is celebrated on March 14. Why that date in particular? Well, the date can be written 3/14, the first three digits of pi!
Pi Day is celebrated on 14 March to honour the mathematical constant pi (π), which has been used in mathematics and geometry for thousands of years. Pi is the ratio of the circumference of a circle to its diameter and is abbreviated to 3.14 but actually has an infinite number of decimal places. We asked Jöran Petersson and Per Blomberg at the Department of Science, Mathematics and Society at Malmö University.
What is the most fascinating thing about pi?
Its simplicity and usefulness. The proportionality perimeter = pi * diameter is easy to understand even for middle school students, while pi is used in many advanced scientific and technological applications.
How is pi used in everyday and scientific contexts?
Pi is used in many fields, for example to calculate the circumference and area of circular objects, and the rotational speeds of rotating objects. One everyday occasion to think about pi is when whipping cream. The electric whisk has a high rotational speed but small radius, while whipping by hand in a large bowl has a lower rotational speed but larger radius. These differences cancel each other out so that the sweep speed, that is, the speed at which the whisk moves through the cream, is approximately the same. Therefore, the whipping time by hand and by machine does not actually differ that much.
Pi is also used in physics for calculations involving mechanical vibrations, radio waves and rotational motion. In digital technology, pi is used in debugging computer chips by testing whether they calculate pi decimals correctly.
Is there any current research at Malmö University involving pi?
At Malmö University, there is research in science and technology and statistics whose calculations use pi.
How do we get young people interested in maths?
By having many methods in your pedagogical toolbox to vary the way you work, explain and use the same concepts when teaching. We endeavour to provide our student teachers with all these tools. I believe this is a key to getting young people to understand and be interested in maths.
More pi?
The understanding of pi has evolved throughout history. Different approximations of pi have been used, from Brahmagupta (c. 600 AD) to Hippocrates (400 BC) and Lindemann (1882) who showed that pi is not a fraction. Jöran Petersson recommends the book Pi - the amazing number by David Blatner. "An easy to read and fun book with lots of oddities and interesting perspectives," he says.
