Copyright © University of Cambridge. All rights reserved.

'Roll On' printed from https://nrich.maths.org/

Show menu


$3$ times

In returning to its original position, the disc rolls a distance $3\pi d$. As the disc does not slip, it rolls out a distance of $\pi d$ when the disc makes one complete turn about its centre, so $3$ complete turns are made.
 
If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.  
This problem is taken from the UKMT Mathematical Challenges.
You can find more short problems, arranged by curriculum topic, in our short problems collection.