Movable pulley

The moter drive will draw up



95 x pi x 65 / 60 = 323.2 mm



of rope per second.



Note that there are 4 pieces of rope pulling the load, hence if the load goes up by x, then the rope has to be drawn by a length of 4x. Therefore the speed of the load is



323.2/4 = 80.8 mm/s



The answer is F.

圖片參考：http://tw.yimg.com/i/tw/ugc/rte/smiley_1.gif