PASCO ME-6807A Human Arm Model - Manual (Page 19)

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Experiment 6: Biceps Force versus Elbow Angle,
Constant Forearm Orientation
Introduction
Hold a mass in your hand with your elbow at 90° so that your upper arm hangs verti-
cally and your forearm is horizontal. While keeping your forearm horizontal, extend
your arm forward as if you are handing the mass to someone.
Predictions
1. As you push the mass forward, does your elbow flex or extend?
2. Does your biceps force increase or decrease?
3. Sketch your prediction of the biceps force versus
elbow angle graph.
Set-up
1. Install the 100 g mass on the model’s hand.
2. Clamp the arm model vertically as illustrated.
3. Use rods and clamps to attach a force sensor
to the base of the model.
4. Attach a cord as illustrated. Adjust the length
of the cord so that the elbow is at 90° when
the shoulder is at 0°. (With this cord arrange-
ment, the forearm will remain approximately
horizontal as the shoulder rotates forward.)
5. Connect the arm model to the angle sensor. Connect the
angle sensor and force sensor to your interface.
6. Set the sampling rate of the force sensor to 20 Hz.
Required Parts of Human Arm Model
Arm
Cord (1 piece)
100 g mass
45 cm rod
Sensor-mounting clamp and stud
Other Required Equipment
Angle Sensor PS-2139
Force Sensor PS-2104 or PS-2189
C-clamp SE-7286 (6-pack)