In Chapter 10 in the textbook, we saw that the Achilles tendon will stretch and then rebound, storing and returning energy during a step. We can model this motion as that of a mass on a spring. This is far from a perfect model, but it does give some insight. If a 60kgkg person stands on a low wall with her full weight on the ball of one foot and the heel free to move, the stretch of the Achilles tendon will cause her center of gravity to lower by about 2.5 mm{\rm mm}.
A) What is the spring constant of her Achilles tendon?
B) If she bounces a little, what is her oscillation period?