1. The problem statement, all variables and given/known data 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. 2. Relevant equations A=Fs 3. 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.