A string of negligible thickness is wrapped several times around a cylinder kept on a rough horizontal surface. A man standing at a distance 1 from the cylinder holds one end of the string and pulls the cylinder towards him (figure 10-Q4). There is no slipping anywhere. The length of the string passed through the hand of the man while the cylinder reaches his hands is
(a) l
(b) 2l
(c) 3l
(d) 4l.
