"Arms, Levers, Balances, and a bit of math"(PDF, 1.1 Mb, print quality graphics)
a three part lab activity that looks primarily at the elbow as a model for studying mechanical advantage.
All parts require hanging masses of various mass. Parts one and two require a spring scale.
The first piece of equipment requires two rulers to be fastened together to create a
lever to model the elbow. The second and third activity use meter stick holders that
can slide along a meter stick and be fastened in one place (search
ScienceKit.com
for "Moment of Force Apparatus" to see a photo that includes the hangers--I couldn't
find the hangers by themselves, but if you call your favorite supply house, they probably
have them). I use large paper clips for hanging the masses, much cheaper and less extra mass (make
sure they can be bent open without breaking--one type I bought broke when they were
bent open.