Where's the centre of rotation? (2)
As in the Starter task 'Where's the centre of rotation (1)', we show a flag being rotated through 90˚, but this time we also show the plane being rotated (or at least part of it).

We can ask, 'Where's the invariant point?'

The two Quicktime movies are very short and almost identical: in Movie A it is possible to visualise the invariant point; in Movie B the invariant point is made explicit.

Note: If needed, you can download a free copy of the QuickTime movie player from here:


Save for later
  • wheres-the-centre-(2)-guide.pdf
  • wheres-the-centre-(2)-Movie-A.mov
  • wheres-the-centre-(2)-Movie-B.mov

About this resource


Created: Jan 17, 2015

Updated: Feb 22, 2018

pdf, 156 KB


mov, 1 MB


mov, 1 MB


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Creative Commons "Sharealike"