## Balance Beam

### Notes:

The Balance Beam Interactive is an adjustable-size file that displays nicely on smart phones, on tablets such as the iPad, on Chromebooks, and on laptops and desktops. The size of the Interactive can be scaled to fit the device that it is displayed on. The compatibility with smart phones, iPads, other tablets, and Chromebooks make it a perfect tool for use in a 1:1 classroom.

### Teaching Ideas and Suggestions:

This Interactive is intended for use in the early stages of a learning cycle on balanced torques and equilibrium. It would be useful for students to have been introduced to the concept of torque and the idea of a fulcrum. However, it is not required that they know much about what is required in order to balance the beam. With very little in the way of directions, students can quickly begin dragging masses onto the balance beam and reposition them in order to balance the beam with different amounts of mass on opposite sides. It is recommended that the challenge of finding the "rule of balance" be presented to students in an open-ended manner. Several questions can be used to frame the exercise, questions like ...

• Is it possible to have two different masses or weights on opposite sides of the fulcrum in order to have a balanced beam? Or must both sides have the same weight?
• If balance can be obtained with different weights, then what other variables are important in determining balance?
• Can you write a mathematical rule that describes the rule of balance for weights placed on opposite sides of the balance beam?

The Physics Classroom has prepared a classroom-ready exercise named The Rule of Balance for use with this Interactive. The exercise allows students to explore the relationship between the weight that hangs from one side of the fulcrum and its distance to the fulcrum to the weight that hangs from the opposite side of the fulcrum and its distance to the fulcrum. Several challenges - beginning with the simple and concluding with the more difficult are presented to students in an effort to guide them to understanding how balanced torques work. The exercise is intended to help students discover the rule of balanced torques without any significant instruction on the topic of torque or balanced torques. The Conclusion to the activity challenges students to make a claim regarding what the rule of balance is; then they must use evidence and reasoning to show how the data support the rule. The exercise can be done quite quickly and serves as a great introduction to the concept of balanced torques. We believe that it would make a great pre-cursor to a hands-on activity that involves hanging actual hooked masses from specific locations along a balanced meter stick.

### Related Resources

Drats! If we had more time, we would have more resources. As of this writing, there are no other resources at The Physics Classroom that pertain to the topic of torque or rotational equilibrium. We expect that this will change someday. We don't know when "someday" is but we assure you that we are pedaling as fast as we can.

### Credits

The Physics Classroom would like to extend a special thanks to Nerd Island Studios for the creation of this HTML5 Interactive. Visit http://www.nerdislandstudios.com to see more great stuff by Nerd Island Studios.

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