videos and websites on buildings and structures

https://www.youtube.com/watch?v=ma9Y97hrsb4      (contact forces)

https://www.youtube.com/watch?v=njGz69B_pUg        (atoms)

https://www.youtube.com/watch?v=j78qLGJzL90   (factors affecting construction of buildings)

https://www.youtube.com/watch?v=c-V_8_qmJbE  (role of force and tension)

http://www.historyofbridges.com/facts-about-bridges/truss-bridge/  (truss bridges)

https://www.youtube.com/watch?v=EYRYtTMcYZM     (bridges types and forces)