In chapter 10 we saw taht the achilles tendon will stretch and thenrebound storing and returning energy durint a step. We can modelthis motion as that of a mass on a spring. This is far from aperfect model but it does give some insight. If a 60kg personstands on a low wall with her full weight on the ball of one footand the heel free to move, the stretch of the achilles tendon willcause her center of gravity to lower by about 2.5mm
a) what is the spring constant of her achilles tendon
b) if she bounces a little, what is her oscillation period
c)when walking or running, the tendon spring begins to stretch asthe ball of the foot takes the weight of a stride, transformingkinetic energy into elastic potential energy. Ideally, the cycle ofthe motion will have advanced so that potential energy has justfinished being converted back to kinetic energy as the foot leavesthe ground. What fraction of an oscillation period should the timebetween landing and liftoff correspond to? Given the period youcalculated above what is this time?
d) Sprinters running a short race keep thier foot in contact withthe ground for about .1s some of which corresponds to the heelstrike and subsequent rolling forward of hte foot. Given this doesthe answer to part c make sense.
In chapter 10 we saw taht the achilles tendon will stretch and thenrebound storing and returning energy durint a step. We can modelthis motion as that of a mass on a spring. This is far from aperfect model but it does give some insight. If a 60kg personstands on a low wall with her full weight on the ball of one footand the heel free to move, the stretch of the achilles tendon willcause her center of gravity to lower by about 2.5mm
a) what is the spring constant of her achilles tendon
b) if she bounces a little, what is her oscillation period
c)when walking or running, the tendon spring begins to stretch asthe ball of the foot takes the weight of a stride, transformingkinetic energy into elastic potential energy. Ideally, the cycle ofthe motion will have advanced so that potential energy has justfinished being converted back to kinetic energy as the foot leavesthe ground. What fraction of an oscillation period should the timebetween landing and liftoff correspond to? Given the period youcalculated above what is this time?
d) Sprinters running a short race keep thier foot in contact withthe ground for about .1s some of which corresponds to the heelstrike and subsequent rolling forward of hte foot. Given this doesthe answer to part c make sense.
