Question

Chapter 12, Problem 013 The figure shows the anatomical structures in the lower leg and foot that are involved in standing on tiptoe, with the heel raised slightly off the floor so that the foot effectively contacts the floor at only at point P. Assume distance a 4.2 cm, distance b- 17 cm, and the person's weight W 830 N. Take the upward direction to be positive. Of the forces acting on the foot, what are (a) the force at point A from the calf muscle, and (b) the force at point B from the lower leg bones? Calf muscle Lower leg bones (a) Number Units (b) Number Units

Answer 1

(A) balancing moment about the point b,

(FA x 4.2) - (17 x 830) = 0

FA = 3359.5 N

(B) Fa + Fb - W = 0

FB = - 2529.5 N

at B, 2529.5 N downward