362 Static Equilibrium and ElasticityP12.30Count the wires. If they are wrapped together so that all support nearly equal stress, the numbershould be20 0100. kN0.200 kN=.Since cross-sectional area is proportional to diameter squared, the diameter of the cable will be11001mmcmaf~.P12.31From the defining equation for the shear modulus, we find ∆xas∆xhfSA==×××=×−−−500 102003 0 1014 0 10238 103645...m NNmmm22ejafejor ∆x−2. mm.P12.32The force acting on the hammer changes its momentum according tomvFtmvif+=∆afso Fmvvtfi=−∆.Hence, F=−−30 010 020 00110818 103...kgm sm ssN.By Newton’s third law, this is also the magnitude of the average force exerted on the spike by thehammer during the blow. Thus, the stress in the spike is:
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