Biomedical Engineering Reference
In-Depth Information
3. Tie the sewing thread to one of the metallic wires so that the arrangement can be
suspended. The strip of rubber must be tied to each metallic wire in the middle as
shown in Fig.
8.8
. The sewing thread and the rubber strip must be tied in a way
that the structure stays in equilibrium when released, and can rotate freely.
4. Fix one large clip near the extremity of each metallic wire. Ensure that the mass
of both metallic wires with clips is the same.
5. Rotate one of the metallic wires clockwise and the other in the counterclockwise
direction, twisting the rubber.
6. Release the arrangement and report what you observe.
7. Change the position of both clips closer to the rubber, in one of the metallic
wires, keeping the other wire as it is. Observe that the masses of each wire with
two clips remain the same. Repeat the procedures 5 and 6.
8. Do you observe a change in the rotational velocity? Why?
9. Explain the reason for the opposite direction of the rotations of wires. Observe
that the arrangement is at rest when it is freed.
Note: You can improve the experiment, increasing the number of clips.
8.7.1 Objectives
• To apply the principle of the lever and the equilibrium conditions of a rigid body
• To classify levers
• To analyze devices that allow the discussion of mechanical advantage
8.7.2 Activity 6: Levers
8.7.2.1 Necessary Materials
- Plank or metallic bar
- Rubber strip spring scale
- Ruler or tape measure
- Adhesive tape
- Calibrated masses
8.7.2.2 Procedure
Take a plank and fix one of the extremities to the workbench with adhesive tape so
that there will be an axis of rotation. Use the adhesive tape to form two support
