Objectives:

• Understand the definition of torque
• Understand the additivity of torque
• Understand that torque balance is necessary for equilibrium
• Compute the torque due to gravity

Materials:

• Flat, narrow metal (magnetic) balance beam
• Fulcrum
• Weights (washer magnets work well)

Activities:

• Challenge a student to balance the beam on the fulcrum, without resorting to trial and error (see if they can calculate the length of the beam divided by 2)
• Stack various configurations on one side, then challenge students to restore balance by using certain weights
• Shift the balance beam so that it is no longer centered over the fulcrum.  Why is it no longer balanced?
• Have the students challenge each other
• Play around by sliding magnets underneath, then having repelling magnets on the table surface, show how this reduces the torque

Discussion questions:

1. How many washers together would have the same weight as the balance beam
2. How might the idea of balancing torques be used to measure weight?
3. Think of some other applications where understanding torque is important