Biomedical Engineering Reference
In-Depth Information
F
2
F
3
F
1
T
F
1
F
2
T
F
3
W
In this example, there is only one cable subject to the weight force
W
, of the
suspended object. The system of pulleys gives rise to the forces
F
1
,
F
2
, and
F
3
whose vector sum gives the force of traction
T
. The vector sum is drawn where the
angle
of the resultant traction with the horizontal is shown. The same angle and
the direction of the line of action of the resultant traction are also represented in the
figure of the system of traction.
θ
Exercise 5.13
Find the magnitude and the direction of the force of traction of the
system of Example 5.3 for the case in which the magnitude of forces obeys
the following specifications: the magnitudes of vectors
F
1
,
F
2
, and
F
3
are equal
and the value is 45 N.
Example 5.4
Determine the intensity and the direction of the traction force in
the fixed pulley attached to the patient under traction, shown in the figure of
Example 5.4.
sin 45
¼
cos 45
¼
0.707.
¼
The intensity of each of the three forces of traction is
50 N. Applying the
condition of equilibrium relative to translation:
