Concepts

Torque

Overview

A weight is fixed at various distances from a handle. As the weight is moved along the bar, the work it takes to pivot the bar upwards about the handle changes noticably.

Details

Equipment

• [1] 1 meter long aluminum bar with a handle
• [2] 500 gram weight
• (Optional) [1] Spring scale
• (Optional) [1] Lab stand
  

Classroom Assembly

1. Place 2 sliding weights near the handle.

Script

1. Get a strong-looking student volunteer to hold the grip bar.
2. Starting with the weights positioned near the handle, the volunteer should attempt to rotate the metal rod so that it is horizontal.
3. Move the weights further away from the handle.
4. Ask the volunteer to rotate the metal rod so that it is horizontal. The volunteer should eventually fail with the weights furthest from the handle.

Optional:

1. Hang the spring scale from the lab stand.
2. Attach the handle of the bar to the spring scale.
3. Slide the weights back and forth to show the force registered by the scale. Note that the weights cannot be slid far along the bar before the scale registers the maximum reading of 100 N.

Additional Resources