Compression and Tension

Today we started to make suspension bridges. We learned about Compression and Tension.
Compression is when things press together

                           
Tension is when things get stretched or pulled out from each other

We made our bridges out of straws and string. Sellotape to stick them to chairs, and some marbles done up in some tissues for our weight.


Next week we will compare the strength of a suspension bridge to a beam bridge.
Post written by Jamie and Tayla

Trip to Pataka

Today we had a trip to Pataka, the museum/art gallery over at Porirua. We marvelled at Peter Trevelyan's sculptures. He builds complex geometric constructions from graphite-pencil leads!

We also had some hands on experience with sculpture. Have a look at our slide show- It was a fantastic time!

How many marbles will the bridge hold?

Mrs Brieseman set us a challenge today- and she set it so at first we were going to flop and then conquer!
First of all we set out some books to act as 2 sides or 'banks' of a river. Then we were given a piece of paper to place across the books and act as a bridge. We had to guess how many marbles would sit on our bridge and we were lucky if 2 would before the whole thing collapsed!

We then folded our piece of paper in half length-ways and again made a guess of how many marbles would our bridge hold. A few more this time, before it collapsed.

Finally, we folded our piece of paper over and over like a fan (corrugated) and placed it on the books.
 

We were amazed at what a difference this made. The bridges held a lot more marbles- up to127 marbles!
With cardboard on either side of our folded paper, our bridge would have been even stronger. Corrugated cardboard has a similar structure