Static Equilibrium Lab
Purpose
To verify that a system at static equilibrium has a negligible net torque.
To determine the mass of an object using a torque balance.
Materials
meterstick
torque pedestal (fulcrum)
Procedure
Determine the centre of mass of the meterstick
Place one knife-edge mass hanger near the middle of the meterstick and place on the fulcrum
Slide the meterstick relative to the hanger until the meterstick is balanced on the fulcrum
Record the position of the meterstick at the fulcrum; this is the centre of mass of the meterstick.
3 knife-edge mass hangers
set of hook masses
unknown mass ____
Balancing masses with centre of mass at the fulcrum
Place a total of three knife-edge mass hangers on the meter stick with the central mass hanger at the
centre of mass of the meterstick and the other two somewhere on each side of its centre of mass
Attach unequal masses to each mass hanger on each side.
Slide one mass along the meterstick until the system is balanced.
Record the position of each mass relative to the fulcrum
Determine and record the mass of each mass and mass hanger
Balancing masses with centre of mass NOT at the fulcrum
Slide the central mass hanger so that the centre of mass of the meterstick is not at the fulcrum
Repeat the above procedure using the same masses
Determining the mass of an unknown
Chose an unknown mass and record its letter
Devise a method for determining the mass of the unknown (include in write up)
Determine the unknown mass
MiniLab Write Up
Procedure
Results
for Determining the mass of an unknown
 3rd person (passive) past tense. ex. The ball was placed at the top of the ramp and released.
 Describe in sufficient detail what was done.
Organized in a table like the one below
Variable
Lever Arm / m
(relative to
)
Mass A
Unknown Mass ____
Meterstick (CoM)
Fulcrum
Net
Calculation
Show how the unknown mass was calculated
Conclusion
State the value of your unknown mass
Force / N
Torque / N  m
0
0
Recommendations for improving the lab would be welcomed but not necessary.