Biomedical Engineering Reference
In-Depth Information
a
b
F
1
F
2
axis
axis
W
W
c
d
F
4
F
3
axis
axis
W
W
Fig. 8.9
Representation of the proposed activity in which the wooden plank is maintained in static
equilibrium through the torque of applied forces
F
and measured by a spring scale, in four different
situations: (
a
), (
b
), (
c
) and (
d
). The weight force
W
is represented at the plank's center of gravity.
The point of application of forces
F
corresponds to the loops made with tape attached to the plank.
The rotation axes correspond to the point where the plank is fixed with the tape to the workbench
loops, placing one near the free extremity as shown in Fig.
8.9a, b
and another, at
any place between the middle of the plank and the axis of rotation as illustrated in
Fig.
8.9c, d
. If the mass of the plank is very small, add a mass by attaching it with
adhesive tape at its center of gravity.
1. To establish static equilibrium in the situations shown in Fig.
8.9
, apply the
necessary force. For this, use the rubber band spring scale and its calibration
curve.
2. For each of the situations:
(a) Measure the force on the spring scale and determine the arms of action and
of resistance (plank weight) force. Consider that the plank is homogenous
and its center of gravity is in its center.
(b) Determine from the static equilibrium conditions:
- The value of the weight of the plank
- The magnitude of the support force (normal reaction) for situations b)
and d)
- The type of lever used
