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Q & A: Screwdrivers and Torque

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Most recent answer: 10/22/2007
Q:
Why does it seems like you can develop more torque with a screwdriver with a longer shaft than with a shorter one (with the same diameter tip and same diameter handle)?
- Roger Kaiser, University of Illinois Alum
West Grove, PA
A:
This may seam odd, but the different length of screwdriver really doesn't affect the torque directly. Torque is the force applied times the distance from the axis you are rotating about. So the torque of the screwdriver only really depends on the thinkness of the handle.

But as you said, there seems to be a difference. I would suspect that you feel more torque because the longer handle gives you more of a grip with your hand. It will be easier for you to apply the force with your hand and that will add more torque.

It is important to note that I wrote this as if you were turning a screw. If insted, you were using the screwdriver to open a can of paint, there is a difference. The long handle will move your hand further from the rotation and give you more torque.

Adam

(published on 10/22/2007)

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