Kinesiology 201 Questions Tissue Mechanics Tony Leyland School of Kinesiology Simon Fraser University Connective Tissue 1 a) In a fall a ligament has 2500 N of tensile force exerted on it. If the area of the crosssectional area of the ligament is 2 cm2 what is the tensile stress on the ligament? [2] b) If the force rises to 3000 N and 10% of the collagen fibres fail (break), what would the tensile stress be now? [2] c) What may happen to the ligament in this situation? Relate your answer to the stress-strain curve for human ligament tissue. [4] 2. How does bone’s viscoelastic properties help reduce the likelihood of fracture? [3] 3. If a tendon was 0.1 m long and was stretched to a length of 0.12 m, what would be the strain experienced by the tendon. What are the units of strain? [2] 4. What are the functions of articular fibrocartilage? [2] 5. a) Using the standard anthropometry given what would the compressive force be across the knee if our 50% male stood with weight evenly distributed between both feet? Assume there is no muscle activity. [3] b) What would happen to this force if the he stood on one foot? [3] c) What would happen if we factored in muscle forces (no calculation needed)? [1] Segment Relative Mass Head 0.073 Trunk 0.507 Upper arm 0.026 Forearm 0.016 Hand 0.007 Thigh 0.103 0.043 7. What is the name given to the undulations seen in Calf Foot 0.015 collagen fibres of an intact ligament? [2] 8. What is the basic composition of bone (yes bone is a connective tissue, albeit a specialised connective tissue) and why is it termed a two-phase material? [4] 6. The table below gives the relative masses (ratio with total body mass) of various body segments. Calculate the average pressure on the L5/S1 vertebral disc (cross sectional area = 25 cm2) of a 90 kg man. Assume that the mass of the trunk is above the L5/S1 joint. [8] 9. Bone is an anisotropic material. What does this mean? Explain the terms you use in this explanation. [5] 1