A cylindrical drum, pushed along by a board rolls forward on the ground. There is no slipping at any contact. The distance moved by the man who is pushing the board, when axis of the cylinder covers a distance `L` will be.

Explanation

Let `v_(0)` be the linear speed of the axis of the cylinder and `omega` be its angular speed about the axis. As it does not slip on the ground hence `omega=v_(0)//R`. Where `R` is the radius of the cylinder.
Speed time taken by the axis of move a distance `L` is equal to `t=L//v_(0)`.
In the same interval of time distance moved by the topmost point is
`S=2v_(0)xxL/(v_(0))=2L`
As there is no slipping between any point of contact hence distance moved by the man is `2L`.