2(a). With the aid of a diagram, explain what a stress-strain graph is. Parkour (or its "acrobatic" version called Freerunning ) has emerged as a non-combative form of military obstacle course training usually performed in urban landscapes. Many maneuvers involve landing on both feet from heights which normally result in injury if not for the exceptional skill and technique of the participants A person can break the long bones of the leg by jumping from a height and landing on his or her feet on hard ground. The most vulnerable weight bearing bone is the tibia, and the compressive stress on this bone will be greatest at the point where the cross-sectional area is least. In other words, just above the ankle.

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