PASCO ME-6807A Human Arm Model - Manual (Page 22)

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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 7 : T r i c e p s E x t e n s i o n
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Procedure
1. Hold the forearm horizontal by pulling with the force sensor.
2. Start data collection.
3. Pull with the force sensor to slowly extend the elbow from about 90° to 10°.
4. Stop data collection.
Analysis
1. As the arm lifts the mass, does elbow angle increase or decrease?
2. Does the triceps force increase or decrease? (Note that the extending motion of
the elbow is represented by right-to-left movement on the graph.)
Part B
Introduction
The motion studied in this part is similar to that of Part A, but the upper arm is held
horizontally rather than vertically.
Hold a mass in your hand. Lean forward and rotate your shoulder back so that your
upper arm is horizontal. Bend your elbow at 90 degrees so that your forearm hangs
straight down. While keeping your upper arm horizontal, lift the mass by extending
your elbow.
Predictions
1. As you lift the mass, does your triceps force increase or decrease?
2. Sketch your prediction of the triceps force versus elbow angle graph.
Set-up
1. Reposition the model’s shoulder and lock it at 90°.
2. Hold force sensor in the position illustrated.
Procedure
1. Start data collection.
2. Pull with the force sensor to slowly extend the
elbow from about 85° to 15°.
3. Stop data collection.
Analysis
Compare this graph to the graph from Part A.