Roberval Balance

This demonstration shows static torque for a more complicated system. Students can calculate the torque at different positions on the balance to see why it levels out in certain cases.

Setup:

Place the balance and masses on the lab table.

If equal masses are placed on the yellow platforms, the system looks unbalanced.

The instructor places a set of masses on one side's outer platform, and an equal set on the other side's inner platform, as shown in the photo. The balance levels out.

Notes:

The calculations involved with this demonstration can take considerable time. Therefore, it might best be done as a homework problem.

Courses Used In:

• PHY 10111

• PHY 10310

• PHY 10410

• PHY 30210

Discussion and Polling Questions:

• What is the net force in the system in each case? The net torque?

• Does the net force in the x-direction help you solve this problem?

• Can you solve the system using one rod?

Equipment Needed:

• Roberval Balance Apparatus

• Masses (Two Equal Sets)