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Re: [Phys-l] 'Torque' question



Statics: r X F = 0 and F = 0

pick r =0 at one of the F's to reduce the calculation(s)

bc minimalist



On 2010, Jul 12, , at 17:21, chuck britton wrote:

At 9:33 PM -0400 7/11/10, Fakhruddin, Hasan wrote:
Greetings folks!
Say a force is applied on an object to rotate it about a hinge. Why
does it get easier (like needing less force) to rotate the object as
the force is applied farther from the hinge?
~ Hasan Fakhruddin

Another approach to this question - one that is often useful for
beginning students taking tests.

What is it that is constant in this problem????
Energy? Momentum? Angular Momentum?
But there is no continuing motion implied here - so maybe something
else is 'constant'.

How about the 'Title' of the problem?
Torque? = r x F


'further from the hinge' => r getting bigger.
r getting bigger => F getting less (if torque stays the same).

HS students want to learn to take tests (as well as learning a bit of
physics perhaps).
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