The way that I can understand how torque works is to say that the greater distance from the rotation axis that you apply your force, the greater power you are delivering to your object - since the farther you are away from the rotational centre the faster something is moving on your rotating object.(adsbygoogle = window.adsbygoogle || []).push({});

But the way my book derives the relationship

(1) Ʃτ = Iα

is kind of mysterious to me, as I don't see where my interpretation shows up during the steps.

They say let F be a force applied to the object. Every i'th particle will experience an acceleration such, that the angular velocity is the same for our rigid body. We thus have:

Fi = mi * a = mi * r * α

And multiplying with r yields:

τi = mi * r^2 * α

And summing over all torques gives us (1) - i.e. the rotational analogue of Newtons 2nd law. All there is left to show is then that the internal torques add to zero, but that's simple. I just don't see where the energy interpretation appears in this derivation - can someone open my eyes? :)

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# Moment of force

Can you offer guidance or do you also need help?

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