There are four main forms of bridge structures, the beam, the cantilever, the arch and the suspension cable. 

How many blocks can you hold?

What is holding the blocks in place? 

What is a bridge that carries water called?

 

 

A bridge carries a road or railway across a river, a valley or another obstacle. The simplest bridge is a beam that is supported at each end by pillars. Beam bridges cannot stretch across wide gaps. An arch bridge pushes outwards against the supports, unlike a beam bridge that transmits its weight vertically on to the supports. On an arch bridge, the supports must be heavy to resist any horizontal thrust of the arch.

When you push the blocks together they are said to be under compression (pushing force). The forces across the structure must be equally distributed or the materials will be broken. It would be difficult for you to do hold the blocks for too long because the muscle in your arms will get tired and start to shake.

Friction

Forces in Action