On the right is a model of the Leaning Tower built by pupils at Dunn Street Primary School in Jarrow.
The challenge was to build the tower then simulate how Professor John Burland (see below) stopped it from falling over and brought it back to a safe angle so that people could start visiting again.
First the class did a series of investigations related to strength of structures and balance. They looked at ways of finding out how strong a structure is and why an object will overbalance and fall. They also found out about the Forces in action in a structure and what these forces can do eg. cause stretching, bending, compression and breaking or ‘shear’.
The tower was tested in a box of sand to simulate the soil conditions under the tower and around the foundations.
The three main investigations on the tower were as follows:
1. Using a cable in tension to stop the tower leaning any further. The cable (a string) was ‘looped’ around the middle of the tower then gradually pulled until it just started to move the tower back to a smaller angle of lean.
2. Heavy weights (jars of marbles and a lump of lead) were added to the base of the tower on the side opposite to the direction of lean. This stopped the tower leaning any further and actually decreased the angle of lean even more. The tension was seen to reduce in the cable and it became slack.
3. Soil (sand in this case) was removed by scooping it out from underneath the tower on the side opposite the direction of lean and this caused the tower to lean less and move back to a safer position.