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# Conservation of Energy & D'Alembert's Principle Problem

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1. I'm doing some question papers as revision and i've got a question that i'm not confident with my answer.

The question is :

My work using Conservation of Energy:

and my work for D'Alembert's is:

I was expecting to get similar results for Work Done, Torque and Power But they are completely different.

I'm guessing there is an error in my working somewhere, but i have been over it a number of times and keep getting the same numbers so i'm missing something. Could anyone offer some insight?

2. (Original post by SteveMcs)
I'm doing some question papers as revision and i've got a question that i'm not confident with my answer.

I'm guessing there is an error in my working somewhere, but i have been over it a number of times and keep getting the same numbers so i'm missing something. Could anyone offer some insight?

Not an expert at this level - never come across D'Alembert's principle.

Regarding conservation of energy.

I'd have thought you needed work done against linear force = 150x5=750 Nm (which in itself is greater than the 583.33 you have for friction).

Work done against bearings = 5 x "angle through which drum turns = 5 x (5/(0.6pi)*(2pi))

Workdone in accelerating the drum =....

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