Hello guzzlers,
As schools break for summer holidays and some of us fly abroad to a newly expensive world, here’s a puzzle that at least may improve the journey out. It’s a conundrum you may have asked yourself the last time you took a plane.
You are in an airport, and you are walking from security to your gate. The distance includes stretches of travelator, or moving walkway, and stretches of floor. You have a constant walking speed, u, and the travelators also have constant speed, v. So, when you are on the travelator you are traveling at u + v.
1. You need to stop to tie your shoe. If tying your shoe always takes the same time, will you get to the gate quicker if you tie your shoe on the travelator, off the travelator or does it make no difference?
2. You have enough energy to walk at faster speed, w, for a fixed time. In order to get to the gate quicker, do you increase your speed when you are on the travelator, off the travelator or does it make no difference?
I’ll open the comments at noon, and will post my answers at 5pm. The submissions here are for me to see how well you do.
Today’s puzzle was devised by the mathematician Terence Tao. More about him when I post the solutions.
If you are reading this on the Guardian app, click where it says ‘Follow Alex Bellos’ and you’ll get an alert when I publish the answer.
I post a puzzle here on a Monday every two weeks. If you want to propose a puzzle for this column, please email me I’d love to hear it.
I’m also the author of three popular maths books including Alex’s Adventures in Numberland and the maths colouring book Snowflake Seashell Star. You can check me out on Twitter, Facebook, Google+, my personal website or my Guardian maths blog.
