PASCO ME-6807A Human Arm Model - Manual (Page 11)

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11
Experiment 2: Biceps Force versus Weight
Introduction
Let your arm hang vertically at your side. While keeping your upper arm vertical,
bend your elbow at 90° so that your forearm is horizontal. Hold your palm up. Have
your partner place a mass in your hand, but don't let your arm move.
Predictions
1. If the mass in your hand is 100 g (so its weight is 0.98 N), how much biceps force
is needed to keep your elbow at 90°? (Assume that your triceps is relaxed.)
2. If you double the mass in your hand (so the load force doubles), does the biceps
force double?
3. If you remove the mass from your hand, does the
biceps force go to zero? Explain your answer.
Set-up
1. Clamp the arm model vertically as illustrated.
2. Clamp the rod to the base of the model as illustrated. Use
the sensor clamp and stud to attach a force sensor to the
rod.
3. Lock the shoulder at 0°.
4. Attach a cord as illustrated. Adjust the length
of the cord so that the elbow is held at about
90°.
5. Connect two force sensors to your interface.
The second force sensor will be held in your
hand and apply the load force to the model’s hand.
6. Set the sampling rate of both force sensors to 20 Hz.
7. Prepare a graph to plot biceps force versus load force.
Required Parts of Human Arm Model
Arm
Cord (1 piece)
45 cm rod
Sensor-mounting clamp and stud
Other Required Equipment
2 Force Sensors PS-2104 or PS-2189
C-clamp SE-7286 (6-pack)
Force Sensor 1
(Biceps Force)