How is Work Calculated for Pulling Up a Curtain?

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SUMMARY

The work done in pulling up a curtain of length 2 meters and mass 1 kg is calculated to be 9.81 Joules. The calculation is based on the formula A = F * s, where the force decreases linearly as the curtain is lifted. The correct approach involves determining the average force exerted over the distance, leading to the conclusion that the work done is mg * L / 2, which results in 9.81 J when using the correct mass. The initial confusion regarding the mass being 2 kg was clarified, confirming the accurate mass as 1 kg.

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Homework Statement



A curtain is rolled up a thin rod. There is no friction. The length of the curtain is l=2m and weight is m=2kg. Find the work done.

EDIT: the mass is 1kg not 2.

Homework Equations



A=Fs

The Attempt at a Solution


The solution is A=9.81J The way I did it was that the work done is the area under the curve on the F/s plot. Since the force needed to pull drops linearly, I simply multiplied mg*l and then I divided that by two. Is this approach valid? The answer is correct.
 
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mg*L/2 equals 19.6 J are you saying that 9.81 J is supposed to be the correct answer? I assumed that the center of mass of the curtain was at L= 1 m and that mass was lifted 1 meter to the top of the window. Work = Force * distance * Cos(0)
 
I mistyped the mass, it is 1kg.
 

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