PASCO ME-6807A Human Arm Model - Manual (Page 16)

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H u m a n A r m M o d e l E x p e r i m e n t 4 : B i c e p s C u r l
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3. Stop data collection.
Analysis
1. Is the graph linear?
2. As the elbow flexes does the biceps force increase or decrease?
Part B
Introduction
The motion studied in this part is similar to that of the last part, but the upper arm is
held at an angle rather than vertical.
Hold a mass in your hand. Rest your elbow on the back of a chair so that your upper
arm is at about 45 degrees from vertical. Starting with your elbow straight, flex your
elbow to lift the mass.
Predictions
1. As you lift the mass, does your biceps force increase or decrease?
2. Sketch your prediction of the biceps force versus elbow angle graph.
Set-up
1. Reposition the shoulder and lock it at 45°.
2. Hold force sensor in the posi-
tion illustrated.
Procedure
1. Start data collection.
2. Pull with the force sensor to slowly flex the
elbow from about 5° to 130°.
3. Stop data collection.
Analysis
1. Is the graph linear?
2. As the elbow flexes does the biceps force increase or decrease?
Further Study
Find a shoulder angle for which the biceps force is nearly constant as the elbow flexes
from 10° to 130°.