Teacher’s notes – PASCO ME-6807A Human Arm Model User Manual

Page 28

H u m a n A r m M o d e l

T e a c h e r ’ s N o t e s

Teacher’s Notes

Experiment 1: Biceps Force versus Perpendicular Load

Typical Result:

Analysis:

1. The rela-

tionship is approximately
proportional with a slope of
about 6. 2. For these typical
results, accurate predictions
would have been: (1) The
biceps muscle resists the
load. (2) The biceps force is
greater than the load force.
(3) For a load of 1 N, the
muscle force is approxi-
mately 6 N.

Further Analysis:

1. Free-body diagram:

2. The linear acceleration of the forearm is zero; therefore, the net force is zero. 3. The angular acceleration is
zero; therefore, the net torque is zero.

Further Study, typical results:

1. The force exerted by the biceps (for a given load) increased for angles greater than or less than 90°. 2. More
biceps force is needed to resisted a load when the muscle is attached at the inner insertion point. Less force is
needed when it is attached at the outer insertion point.

force

applied by
upper arm

biceps

force

load

force