So yesterday I posted a question about whether a plane on a treadmill runway would take off and most people say No it won’t… which is actually wrong it will take off…

Why?

Well you see people learn by a sort of “pattern recognition” if we don’t know anything about something we’ll make a comparison between it and something we do know something about and then base our assumptions on that. Everyone thinks about running on a treadmill which is very different to putting a plane on a treadmill.

So lets change this slightly, lets forget about the plane for a moment and replace it with something we all understand… roller skates (or roller blades)…

Stand on level ground with Roller skates on and have someone push you forward… which way do you go? Forward right? (assuming of course you can balance on the stupid things… I can’t.) Now stand on a treadmill switch it on and have someone push you forward the instant the treadmill switches on… which way do you move? Forward right?

Why? Because there is nothing to counter act the force of the person pushing you… all the treadmill does is make your roller skate’s wheels turn faster, because the wheels turn freely the treadmill is unable to “grip” you and pull you backwards.. of course if there is no force acting on you.. you’re standing still then you’ll be pulled backwards by the treadmill.

Now replace yourself and the roller skates with a plane and the friend pushing you with the thrust from the engine of the plane… which way will the plane move? Forward of course… and because the plane is moving forward it will reach it’s take off speed and take off.
The neat thing about this question is that your first “gut” reaction is to say no it won’t take off…? but if you think about it… you suddenly “get it”, well hopefully.

This is one of those “brain teaser” type questions that take you out of your comfort zone and asked you a question about something that you know very little about or at least think you know very little about… but if you did basic science (physics) in school you could actually answer the question.

There are lots of these types of questions and they’re often used in interviews, the most famous are probably the Microsoft Interview Questions…? One’s like “Why are Manhole covers round?”

You probably wouldn’t get the Plane on a treadmill question while interviewing at Microsoft but you might get it while applying for an entrance to an Aeronautic Engineering course or Job.

The plane question was originally asked in an exam paper for Aeronautical Engineering and the correct answer is “Yes it will take off”.