It depends how far and how fast you intend to propel the iron cylinder. (It also depends whether that cylinder is magnetic, and how much friction you need to overcome, and how long it is, and so on.) What are you trying to achieve?
It depends how far and how fast you intend to propel the iron cylinder. (It also depends whether that cylinder is magnetic, and how much friction you need to overcome, and how long it is, and so on.) What are you trying to achieve?