Posted on 02 May 2011 at 10:38h

A week or two ago my first year students did a design experiment with two strips of meccano. One of them decided to build a T pendulum and investigate the relationship between the time period and the distance between the pivot and the cross piece. I thought the result would be like the pendulum, as the cross piece moves up the pendulum is in effect getting shorter so time period should decrease however it's not that simple. The results show that as the strip is moved up the time period gets shorter up to a certain point when it starts to get longer again. If you think about the pendulum is made up of the vertical strip with its mass acting at the centre and the cross piece which just acts as a movable mass. As the mass is moved up the pendulum length gets shorter but when the mass is attached to the pivot then it will have no effect so the length will be effectively longer this means that there must be some turning point where the time period stops getting shorter and starts to get longer again.

Hmm, confusing.