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Q & A: Torque Demos

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Most recent answer: 10/22/2007
Q:
I have to do a presentation on rotation and torque for my physics class any ideas? It’s suppose to be geared towards elementary age children.
- Elizabeth Oliveira (age 19)
Indiana, PA USA
A:
Elizabeth,

On of my favorite torque demos is to show the class different sized wrenches. They all know that the bigger wrenches are good for loosening big stuck nuts etc, but perhaps they did not know that the fundamental reason for this is that the bigger lever-arm provided by these tools allows the user to put a bigger torque (twist) on the nut.

The kids probably also have the correct idea that the best thing to do with a wrench is to push or pull on the handle at right angles to the handle.

Both notions (long lever arm and pushing at right angles) come about because torque is the product of the lever arm and the perpendicular component of the applied force. The best way to maximize this is to apply the force at right angles to the lever-arm, as far as possible from the axis or rotation.

Mats

(published on 10/22/2007)

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