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Unformatted text preview: spine. a) Calculate the total forwardbending moment at the vertebra shown exerted by the external forces in each of the 3 following cases in which a person picks up a weight of 300 N (denoted P), which is pulled by a force of 1 N. The weight of the upper torso of the person is 450 N (denoted W). i) L w is 27cm, L p is 42cm; H is 30cm ii) L w is 19cm, L p is 37cm; H is 30cm iii) L w is 26cm, L p is 52cm; H is 30cm. Figure 3 b) Assuming zero moment at the disc, calculate the force produced by the contraction of the erector spinae muscle (M) in the last case, which acts at a lever arm of 0.05m from the lumbar disc and at the same angle as the spine, which is 35 degrees from vertical. c) Calculate for the last case the total reaction force, R, on the disc and the angle at which it acts. (Hint: this reaction force does not act at the same angle as the muscle force, M) 1 N 1 N 1 N H H H...
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 Winter '06
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