9-1

http://twyfordigcsephysics.blogspot.co.uk/2013/05/elasticity.html

9-1

http://twyfordigcsephysics.blogspot.co.uk/2013/04/moments-and-bridges.html

9-2

http://twyfordigcsephysics.blogspot.co.uk/2013/04/moments-and-bridges.html

9-2

http://twyfordigcsephysics.blogspot.co.uk/2013/04/centre-of-gravity.html

9-1

http://twyfordigcsephysics.blogspot.co.uk/2013/04/centre-of-gravity.html