Age 16 to 18 Challenge Level:
Clearly the bridge will be pulling down on the supports so they
will be exerting an upwards reaction force on their supporting pin
joints. What does the direction of the reaction force tell us about
the forces in the diagaonal support? What does this imply about the
direction of the forces in the next strut?
Once you have understood the principles which allow you to
determine the locations of tensions and compressions in the bridges
you should be able to fill in a picture of tensions and
compressions without the need for any numerical calculations.