How Do You Calculate the Center of Mass of a Human Leg?

[flip290]

Homework Statement

To keep the calculations fairly simple, but still reasonable, we shall model a human leg that is 92.0cm long (measured from the hip joint) by assuming that the upper leg and the lower leg (which includes the foot) have equal lengths and that each of them is uniform. For a 70.0kg person, the mass of the upper leg would be 8.60kg , while that of the lower leg (including the foot) would be 5.30kg .
Find the -coordinate of the center of mass of this leg, relative to the hip joint, if it is stretched out horizontally.

Homework Equations

x_cm= (m_ax_a +m_bx_b)/(m_a+ m_b)

The Attempt at a Solution

x_cm= ((8.6*23) + (5.3*69))/ (13.9)=40.5cm

However, this has come back as incorrect. Where do I go from here?

 

[tiny-tim]

hi flip290!

x_cm= ((8.6*23) + (5.3*69))/ (13.9)=40.5cm

looks ok to me

have you tried two significant figures?​