Biomedical Engineering Reference
In-Depth Information
Fig. 8.11
Association in
series of three rubber strip
spring scales
8.8.2.3 Association of Springs
In this experiment the rubber strip is used. Its behavior is not the same as a spring, as
the relation between the magnitude of the applied force,
F
, and
x
is not constant,
Δ
but, in any case, there is a relation between these quantities.
As in the case of springs, we can associate rubber strips in series and in parallel
and quantify the relation between
Δ
x
and applied
F
for the association.
8.8.2.4 Procedure
1. Construct three spring scales identical to those of Activity 1 of this chapter.
Assume that the rubber strip of each apparatus, being of the same length,
obeys the same calibration curve relating
F
and
x
, already determined for
Δ
that spring scale.
Association in Series
2. Use three spring scales in a series association as illustrated in Fig.
8.11
.
3. Measure the initial length,
x
o,
of association, without any applied force. You can
measure the length of associations, considering the distance between the extrem-
ity of the first clip and the extremity of the last clip. Thus, the measured length is
6 clips + 3 rubber strips.
4. Submit the association in series of the spring scales to a known force (it can be a
pet bottle with water) and determine the increase in the length of the association.
Write the result in Table
8.3
. As the length of the clip does not change, what is
measured now is the length of 6 clips plus 3 elongated rubbers. When
x
is
Δ
