Biomedical Engineering Reference
In-Depth Information
Fig. 5.11
Combination of
two fixed pulleys with two
suspended movable pulleys,
each one with an even
number of forces
F
A
250 kg
from the ground up to height
h
with a system of pulleys with mechanical advantage
two, (
F
A
¼
W
/2), we have to pull a cable with length
d
, which will be twice the
height,
d
¼
2
h
. Thus, the work:
τ ¼
F
A
d
¼
Wh
:
5.6.2 Traction Systems
In different health treatment modalities, mainly that of orthopedics related to
fractures, it will be necessary to immobilize the affected region, to ease its weight,
and even exert traction during the treatment. For this, a system of pulleys can be
employed. The following examples exploit some of these systems.
Example 5.1
Find the magnitude and direction of the traction force exerted on the
patient's leg represented in the figure of Example 5.1. The two pulleys are in the
same plane.
15°
15°
6 kg
6 kg
