PreLab Question:
Consider the model of a person bending forward to lift a 200-N object. The spine and upper body
are represented as a uniform horizontal rod of weight 350 N, pivoted at the base of the spine. The
erector spinalis muscle, attached at a point two-thirds of the way up the spine, is angled at 12.0°
from the spine. Find all Forces
TBy muscle on Spine
NBy joint socet on Spine
FBy arm on Spine
WBy Earth on Spine
The Free-Body diagram shown is called an extended FBD because the forces are placed on the
object at the location where they are applied. This is necessary when calculating torque so that the
moment arm (radius) can be identified.
Force
Caused
BY
ON
X
W
F
N
T
Write equations for a static
equilibrium condition.
Solve for the Tension force in the muscle.
Solve for the Normal force at the pivot joint and its direction.
Y
Torque ()